From 114a5e8aea9e57d477dc23b6d875badd574ef7ae Mon Sep 17 00:00:00 2001
From: Ed Chalstrey <edwardchalstrey@gmail.com>
Date: Wed, 3 Jun 2026 13:18:47 +0100
Subject: [PATCH 01/12] feat: add get_inbook_template to bibtex formatting
 utilities

---
 doc/conf.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/doc/conf.py b/doc/conf.py
index 7d2f1aec9..18796ca96 100644
--- a/doc/conf.py
+++ b/doc/conf.py
@@ -156,6 +156,9 @@ def get_incollection_template(self, e):
             self.format_web_refs(e),
         ]
 
+    def get_inbook_template(self, e):
+        return self.get_incollection_template(e)
+
     def get_inproceedings_template(self, e):
         return toplevel[
             sentence[

From 964f3d7010820f1da209161cfd8245bd0b351bef Mon Sep 17 00:00:00 2001
From: Ed Chalstrey <edwardchalstrey@gmail.com>
Date: Wed, 3 Jun 2026 14:49:41 +0100
Subject: [PATCH 02/12] feat: implement dynamic loading of OpenSpiel games via
 pygambit.catalog

---
 doc/catalog.rst                               | 19 ++++
 .../openspiel.ipynb                           | 37 +-------
 src/pygambit/catalog.py                       | 46 +++++++++
 tests/test_catalog.py                         | 93 +++++++++++++++++++
 4 files changed, 163 insertions(+), 32 deletions(-)

diff --git a/doc/catalog.rst b/doc/catalog.rst
index 2c90df4c8..8f554a5f7 100644
--- a/doc/catalog.rst
+++ b/doc/catalog.rst
@@ -6,4 +6,23 @@ Catalog of games
 Below is a complete list of games included in Gambit's catalog.
 Check out the :ref:`pygambit API reference <pygambit-catalog>` for instructions on how to search and load these games in Python, and the :ref:`Updating the games catalog <updating-catalog>` guide for instructions on how to contribute new games to the catalog.
 
+.. _catalog-openspiel:
+
+Loading OpenSpiel games
+-----------------------
+
+Games from the `OpenSpiel <https://openspiel.readthedocs.io/en/latest/games.html>`_ library
+can be loaded dynamically using the ``open_spiel/`` prefix:
+
+.. code-block:: python
+
+   pygambit.catalog.load("open_spiel/matrix_rps")
+   pygambit.catalog.load("open_spiel/tiny_hanabi")
+
+This requires ``open_spiel`` to be installed (``pip install open_spiel``;
+not available on Windows). The game is exported to NFG or EFG format on the fly
+and loaded into Gambit. Not all OpenSpiel games can be exported; a
+:class:`ValueError` is raised for games that are incompatible with either format.
+See the OpenSpiel interoperability tutorial for worked examples.
+
 .. include:: catalog_table.rst
diff --git a/doc/tutorials/interoperability_tutorials/openspiel.ipynb b/doc/tutorials/interoperability_tutorials/openspiel.ipynb
index fc8fe8be7..edcf7a054 100644
--- a/doc/tutorials/interoperability_tutorials/openspiel.ipynb
+++ b/doc/tutorials/interoperability_tutorials/openspiel.ipynb
@@ -30,14 +30,11 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "from io import StringIO\n",
-    "\n",
     "import matplotlib.pyplot as plt\n",
     "import numpy as np\n",
     "import pyspiel\n",
     "from open_spiel.python import rl_environment\n",
     "from open_spiel.python.algorithms import tabular_qlearner\n",
-    "from open_spiel.python.algorithms.gambit import export_gambit\n",
     "from open_spiel.python.egt import dynamics\n",
     "from open_spiel.python.egt.utils import game_payoffs_array\n",
     "\n",
@@ -150,18 +147,7 @@
    "id": "045cf8dd",
    "metadata": {},
    "source": [
-    "OpenSpiel can generate an NFG representation of the game loadable in Gambit:"
-   ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": null,
-   "id": "f5fa4e42",
-   "metadata": {},
-   "outputs": [],
-   "source": [
-    "nfg_matrix_rps_game = pyspiel.game_to_nfg_string(ops_matrix_rps_game)\n",
-    "nfg_matrix_rps_game"
+    "Gambit's catalog module can load games from the OpenSpiel library directly:\n"
    ]
   },
   {
@@ -169,7 +155,6 @@
    "id": "70d1df64",
    "metadata": {},
    "source": [
-    "Now let's load the NFG in Gambit. Since Gambit's `read_nfg` function expects a file like object, we'll convert the string with `io.StringIO`.\n",
     "We can also add labels for the actions to make the output more interpretable:"
    ]
   },
@@ -180,7 +165,7 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "gbt_matrix_rps_game = gbt.read_nfg(StringIO(nfg_matrix_rps_game))\n",
+    "gbt_matrix_rps_game = gbt.catalog.load(\"open_spiel/matrix_rps\")\n",
     "\n",
     "gbt_matrix_rps_game.title = \"Rock-Paper-Scissors\"\n",
     "\n",
@@ -462,19 +447,8 @@
    "source": [
     "## Extensive-form games from the OpenSpiel library\n",
     "\n",
-    "For extensive-form games, OpenSpiel can export to the EFG format used by Gambit. Here we demonstrate this with **Tiny Hanabi**, loaded from the OpenSpiel [game library](https://openspiel.readthedocs.io/en/latest/games.html):"
-   ]
-  },
-  {
-   "cell_type": "code",
-   "execution_count": null,
-   "id": "02a42600",
-   "metadata": {},
-   "outputs": [],
-   "source": [
-    "ops_hanabi_game = pyspiel.load_game(\"tiny_hanabi\")\n",
-    "efg_hanabi_game = export_gambit(ops_hanabi_game)\n",
-    "efg_hanabi_game"
+    "For extensive-form games, Gambit's catalog module can load games from the OpenSpiel library.\n",
+    "Here we demonstrate this with **Tiny Hanabi**, from the OpenSpiel [game library](https://openspiel.readthedocs.io/en/latest/games.html):\n"
    ]
   },
   {
@@ -482,7 +456,6 @@
    "id": "fa354c9f",
    "metadata": {},
    "source": [
-    "Now let's load the EFG in Gambit.\n",
     "We can then compute equilibria strategies for the players as usual:"
    ]
   },
@@ -493,7 +466,7 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "gbt_hanabi_game = gbt.read_efg(StringIO(efg_hanabi_game))\n",
+    "gbt_hanabi_game = gbt.catalog.load(\"open_spiel/tiny_hanabi\")\n",
     "eqm = gbt.nash.lcp_solve(gbt_hanabi_game).equilibria[0]"
    ]
   },
diff --git a/src/pygambit/catalog.py b/src/pygambit/catalog.py
index 961c2a532..84157263a 100644
--- a/src/pygambit/catalog.py
+++ b/src/pygambit/catalog.py
@@ -1,3 +1,4 @@
+import io
 from importlib.resources import as_file, files
 from pathlib import Path
 from typing import Any
@@ -19,6 +20,48 @@
     ".efg": gbt.read_efg,
 }
 
+_OPENSPIEL_PREFIX = "open_spiel/"
+
+
+def _load_from_openspiel(game_name: str) -> gbt.Game:
+    """
+    Load a game from the OpenSpiel library by name.
+
+    Tries NFG export first; falls back to EFG export via the
+    open_spiel.python.algorithms.gambit exporter. Raises ImportError
+    if open_spiel is not installed, ValueError if the game cannot be
+    exported to either format.
+    """
+    try:
+        import pyspiel
+        from open_spiel.python.algorithms.gambit import export_gambit
+    except ImportError as exc:
+        raise ImportError(
+            "open_spiel is required to load OpenSpiel games. "
+            "Install it with: pip install open_spiel"
+        ) from exc
+
+    try:
+        game = pyspiel.load_game(game_name)
+    except Exception as exc:
+        raise ValueError(f"Could not load OpenSpiel game '{game_name}': {exc}") from exc
+
+    # Try NFG first (works for normal-form games)
+    try:
+        nfg_str = pyspiel.game_to_nfg_string(game)
+        return gbt.read_nfg(io.StringIO(nfg_str))
+    except Exception:
+        pass
+
+    # Fall back to EFG export
+    try:
+        efg_str = export_gambit(game)
+        return gbt.read_efg(io.StringIO(efg_str))
+    except Exception as exc:
+        raise ValueError(
+            f"OpenSpiel game '{game_name}' could not be exported to NFG or EFG format."
+        ) from exc
+
 
 def load(slug: str) -> gbt.Game:
     """
@@ -41,6 +84,9 @@ def load(slug: str) -> gbt.Game:
     """
     slug = str(Path(slug)).replace("\\", "/")
 
+    if slug.startswith(_OPENSPIEL_PREFIX):
+        return _load_from_openspiel(slug[len(_OPENSPIEL_PREFIX):])
+
     # Try to load from file
     for suffix, reader in READERS.items():
         resource_path = _CATALOG_RESOURCE / f"{slug}{suffix}"
diff --git a/tests/test_catalog.py b/tests/test_catalog.py
index c034a3cbd..9492ae6cd 100644
--- a/tests/test_catalog.py
+++ b/tests/test_catalog.py
@@ -1,3 +1,6 @@
+import sys
+from unittest.mock import MagicMock
+
 import pandas as pd
 import pytest
 
@@ -172,3 +175,93 @@ def test_catalog_games_include_descriptions():
     games_with_desc = gbt.catalog.games(include_descriptions=True)
     assert "Description" in games_with_desc.columns
     assert "Download" in games_with_desc.columns
+
+
+# ---------------------------------------------------------------------------
+# OpenSpiel dynamic loading tests (all mocked; open_spiel need not be installed)
+# ---------------------------------------------------------------------------
+
+_MOCK_NFG = gbt.Game.new_table([2, 2]).to_nfg()
+_MOCK_EFG = gbt.catalog.load("bagwell1995").to_efg()
+
+
+def _setup_pyspiel_mock(
+    monkeypatch,
+    *,
+    nfg_str=None,
+    nfg_raises=None,
+    efg_str=None,
+    efg_raises=None,
+    load_raises=None,
+):
+    """Inject a fake pyspiel + open_spiel.python.algorithms.gambit into sys.modules."""
+    mock_ps = MagicMock()
+    mock_export_fn = MagicMock()
+
+    if load_raises is not None:
+        mock_ps.load_game.side_effect = load_raises
+    else:
+        mock_ps.load_game.return_value = MagicMock()
+
+    if nfg_raises is not None:
+        mock_ps.game_to_nfg_string.side_effect = nfg_raises
+    else:
+        mock_ps.game_to_nfg_string.return_value = nfg_str
+
+    if efg_raises is not None:
+        mock_export_fn.side_effect = efg_raises
+    else:
+        mock_export_fn.return_value = efg_str
+
+    mock_gambit_module = MagicMock()
+    mock_gambit_module.export_gambit = mock_export_fn
+
+    monkeypatch.setitem(sys.modules, "pyspiel", mock_ps)
+    monkeypatch.setitem(sys.modules, "open_spiel", MagicMock())
+    monkeypatch.setitem(sys.modules, "open_spiel.python", MagicMock())
+    monkeypatch.setitem(sys.modules, "open_spiel.python.algorithms", MagicMock())
+    monkeypatch.setitem(sys.modules, "open_spiel.python.algorithms.gambit", mock_gambit_module)
+    return mock_ps, mock_export_fn
+
+
+def test_openspiel_load_nfg_success(monkeypatch):
+    """NFG export succeeds: catalog.load returns a valid Game."""
+    _setup_pyspiel_mock(monkeypatch, nfg_str=_MOCK_NFG)
+    game = gbt.catalog.load("open_spiel/matrix_rps")
+    assert isinstance(game, gbt.Game)
+
+
+def test_openspiel_load_efg_fallback(monkeypatch):
+    """NFG export fails, EFG export succeeds: catalog.load returns a valid Game."""
+    _setup_pyspiel_mock(
+        monkeypatch,
+        nfg_raises=RuntimeError("nfg not supported"),
+        efg_str=_MOCK_EFG,
+    )
+    game = gbt.catalog.load("open_spiel/tiny_hanabi")
+    assert isinstance(game, gbt.Game)
+
+
+def test_openspiel_load_import_error(monkeypatch):
+    """Missing open_spiel raises ImportError with a helpful message."""
+    monkeypatch.setitem(sys.modules, "pyspiel", None)
+    with pytest.raises(ImportError, match="open_spiel"):
+        gbt.catalog.load("open_spiel/matrix_rps")
+
+
+def test_openspiel_load_game_not_found(monkeypatch):
+    """pyspiel.load_game failure raises ValueError."""
+    _setup_pyspiel_mock(monkeypatch, load_raises=RuntimeError("unknown game"))
+    with pytest.raises(ValueError, match="bogus_game"):
+        gbt.catalog.load("open_spiel/bogus_game")
+
+
+def test_openspiel_load_export_failure(monkeypatch):
+    """Both NFG and EFG exports fail: raises ValueError."""
+    _setup_pyspiel_mock(
+        monkeypatch,
+        nfg_raises=RuntimeError("nfg not supported"),
+        efg_raises=RuntimeError("efg not supported"),
+    )
+    with pytest.raises(ValueError, match="could not be exported"):
+        gbt.catalog.load("open_spiel/matrix_rps")

From 4684cc1892a62408b79a1907cb7936afe9329194 Mon Sep 17 00:00:00 2001
From: Ed Chalstrey <edwardchalstrey@gmail.com>
Date: Wed, 3 Jun 2026 15:10:02 +0100
Subject: [PATCH 03/12] feat: suppress C-level stderr during OpenSpiel NFG
 exports to prevent unwanted console output

---
 src/pygambit/catalog.py | 34 ++++++++++++++++++++++++++++++++--
 1 file changed, 32 insertions(+), 2 deletions(-)

diff --git a/src/pygambit/catalog.py b/src/pygambit/catalog.py
index 84157263a..94dfc7ad3 100644
--- a/src/pygambit/catalog.py
+++ b/src/pygambit/catalog.py
@@ -1,4 +1,6 @@
+import contextlib
 import io
+import os
 from importlib.resources import as_file, files
 from pathlib import Path
 from typing import Any
@@ -23,6 +25,30 @@
 _OPENSPIEL_PREFIX = "open_spiel/"
 
 
+@contextlib.contextmanager
+def _suppress_c_stderr():
+    """Redirect C-level stderr (fd 2) to /dev/null for the duration of the block.
+
+    This prevents OpenSpiel's C++ code from printing error messages (e.g.
+    "OpenSpiel exception: Must be a normal-form game") to the user's terminal or
+    notebook when we speculatively attempt an export that may not be supported.
+    Falls back silently if the fd-level redirect is unavailable (e.g. Windows).
+    """
+    try:
+        devnull_fd = os.open(os.devnull, os.O_WRONLY)
+        saved_fd = os.dup(2)
+        os.dup2(devnull_fd, 2)
+        os.close(devnull_fd)
+    except OSError:
+        yield
+        return
+    try:
+        yield
+    finally:
+        os.dup2(saved_fd, 2)
+        os.close(saved_fd)
+
+
 def _load_from_openspiel(game_name: str) -> gbt.Game:
     """
     Load a game from the OpenSpiel library by name.
@@ -46,9 +72,13 @@ def _load_from_openspiel(game_name: str) -> gbt.Game:
     except Exception as exc:
         raise ValueError(f"Could not load OpenSpiel game '{game_name}': {exc}") from exc
 
-    # Try NFG first (works for normal-form games)
+    # Try NFG first (works for normal-form games).
+    # Suppress C-level stderr so OpenSpiel's C++ error message for non-NFG games
+    # (e.g. "OpenSpiel exception: Must be a normal-form game") is not shown when
+    # we fall through to the EFG path.
     try:
-        nfg_str = pyspiel.game_to_nfg_string(game)
+        with _suppress_c_stderr():
+            nfg_str = pyspiel.game_to_nfg_string(game)
         return gbt.read_nfg(io.StringIO(nfg_str))
     except Exception:
         pass

From f3e111974add5b71e44c84ae618c3f603a201ae5 Mon Sep 17 00:00:00 2001
From: Ed Chalstrey <edwardchalstrey@gmail.com>
Date: Wed, 3 Jun 2026 15:15:02 +0100
Subject: [PATCH 04/12] Update tutorial text in interoperability notebook

---
 .../interoperability_tutorials/openspiel.ipynb     | 14 +++-----------
 1 file changed, 3 insertions(+), 11 deletions(-)

diff --git a/doc/tutorials/interoperability_tutorials/openspiel.ipynb b/doc/tutorials/interoperability_tutorials/openspiel.ipynb
index edcf7a054..eed31fa09 100644
--- a/doc/tutorials/interoperability_tutorials/openspiel.ipynb
+++ b/doc/tutorials/interoperability_tutorials/openspiel.ipynb
@@ -147,15 +147,7 @@
    "id": "045cf8dd",
    "metadata": {},
    "source": [
-    "Gambit's catalog module can load games from the OpenSpiel library directly:\n"
-   ]
-  },
-  {
-   "cell_type": "markdown",
-   "id": "70d1df64",
-   "metadata": {},
-   "source": [
-    "We can also add labels for the actions to make the output more interpretable:"
+    "Gambit's catalog module can load games from the OpenSpiel library directly (here we also add a title and action labels to make the output more interpretable):\n"
    ]
   },
   {
@@ -447,7 +439,7 @@
    "source": [
     "## Extensive-form games from the OpenSpiel library\n",
     "\n",
-    "For extensive-form games, Gambit's catalog module can load games from the OpenSpiel library.\n",
+    "We can also load extensive-form games via Gambit's catalog module.\n",
     "Here we demonstrate this with **Tiny Hanabi**, from the OpenSpiel [game library](https://openspiel.readthedocs.io/en/latest/games.html):\n"
    ]
   },
@@ -853,7 +845,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.13.5"
+   "version": "3.13.13"
   }
  },
  "nbformat": 4,

From b2fe21500e180fe9523d19892de8368804a99367 Mon Sep 17 00:00:00 2001
From: Ed Chalstrey <edwardchalstrey@gmail.com>
Date: Wed, 3 Jun 2026 15:24:22 +0100
Subject: [PATCH 05/12] docs: reorganise catalog page by moving the table
 inclusion and OpenSpiel sections under dedicated headers

---
 doc/catalog.rst | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/doc/catalog.rst b/doc/catalog.rst
index 8f554a5f7..43de13897 100644
--- a/doc/catalog.rst
+++ b/doc/catalog.rst
@@ -5,6 +5,12 @@ Catalog of games
 
 Below is a complete list of games included in Gambit's catalog.
 Check out the :ref:`pygambit API reference <pygambit-catalog>` for instructions on how to search and load these games in Python, and the :ref:`Updating the games catalog <updating-catalog>` guide for instructions on how to contribute new games to the catalog.
+Games from the OpenSpiel library are also available; see :ref:`Loading OpenSpiel games <catalog-openspiel>`.
+
+Loading Gambit games
+-----------------------
+
+.. include:: catalog_table.rst
 
 .. _catalog-openspiel:
 
@@ -24,5 +30,3 @@ not available on Windows). The game is exported to NFG or EFG format on the fly
 and loaded into Gambit. Not all OpenSpiel games can be exported; a
 :class:`ValueError` is raised for games that are incompatible with either format.
 See the OpenSpiel interoperability tutorial for worked examples.
-
-.. include:: catalog_table.rst

From c411543f8f619db2399b4c3f9c48e3bb7f78d514 Mon Sep 17 00:00:00 2001
From: Ed Chalstrey <edwardchalstrey@gmail.com>
Date: Wed, 3 Jun 2026 15:25:36 +0100
Subject: [PATCH 06/12] Remice superfluous header and add link

---
 doc/catalog.rst | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/doc/catalog.rst b/doc/catalog.rst
index 43de13897..6090f53d8 100644
--- a/doc/catalog.rst
+++ b/doc/catalog.rst
@@ -7,9 +7,6 @@ Below is a complete list of games included in Gambit's catalog.
 Check out the :ref:`pygambit API reference <pygambit-catalog>` for instructions on how to search and load these games in Python, and the :ref:`Updating the games catalog <updating-catalog>` guide for instructions on how to contribute new games to the catalog.
 Games from the OpenSpiel library are also available; see :ref:`Loading OpenSpiel games <catalog-openspiel>`.
 
-Loading Gambit games
------------------------
-
 .. include:: catalog_table.rst
 
 .. _catalog-openspiel:
@@ -29,4 +26,4 @@ This requires ``open_spiel`` to be installed (``pip install open_spiel``;
 not available on Windows). The game is exported to NFG or EFG format on the fly
 and loaded into Gambit. Not all OpenSpiel games can be exported; a
 :class:`ValueError` is raised for games that are incompatible with either format.
-See the OpenSpiel interoperability tutorial for worked examples.
+See the :doc:`OpenSpiel interoperability tutorial <tutorials/interoperability_tutorials/openspiel>` for worked examples.

From cdd3ece04dc11db7476d126b9863aac4d007fc30 Mon Sep 17 00:00:00 2001
From: Ed Chalstrey <edwardchalstrey@gmail.com>
Date: Wed, 3 Jun 2026 15:53:35 +0100
Subject: [PATCH 07/12] docs: convert OpenSpiel heading to rubric in catalog
 documentation

---
 doc/catalog.rst | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/doc/catalog.rst b/doc/catalog.rst
index 6090f53d8..3b6551a99 100644
--- a/doc/catalog.rst
+++ b/doc/catalog.rst
@@ -11,8 +11,7 @@ Games from the OpenSpiel library are also available; see :ref:`Loading OpenSpiel
 
 .. _catalog-openspiel:
 
-Loading OpenSpiel games
------------------------
+.. rubric:: Loading OpenSpiel games
 
 Games from the `OpenSpiel <https://openspiel.readthedocs.io/en/latest/games.html>`_ library
 can be loaded dynamically using the ``open_spiel/`` prefix:

From f0fee0aaa39ba30d5fa040bee67ddc6324f4d77f Mon Sep 17 00:00:00 2001
From: Ed Chalstrey <edwardchalstrey@gmail.com>
Date: Thu, 4 Jun 2026 10:27:45 +0100
Subject: [PATCH 08/12] refactor: prioritize EFG export over NFG in OpenSpiel
 game loading and update tests accordingly

---
 src/pygambit/catalog.py | 19 +++++++++----------
 tests/test_catalog.py   | 22 +++++++++++-----------
 2 files changed, 20 insertions(+), 21 deletions(-)

diff --git a/src/pygambit/catalog.py b/src/pygambit/catalog.py
index 94dfc7ad3..f3fb17a4c 100644
--- a/src/pygambit/catalog.py
+++ b/src/pygambit/catalog.py
@@ -72,24 +72,23 @@ def _load_from_openspiel(game_name: str) -> gbt.Game:
     except Exception as exc:
         raise ValueError(f"Could not load OpenSpiel game '{game_name}': {exc}") from exc
 
-    # Try NFG first (works for normal-form games).
-    # Suppress C-level stderr so OpenSpiel's C++ error message for non-NFG games
-    # (e.g. "OpenSpiel exception: Must be a normal-form game") is not shown when
-    # we fall through to the EFG path.
+    # Try EFG first (works for extensive-form games).
+    # Suppress C-level stderr so any C++ error messages for games that don't
+    # support EFG export are not shown when we fall through to the NFG path.
     try:
         with _suppress_c_stderr():
-            nfg_str = pyspiel.game_to_nfg_string(game)
-        return gbt.read_nfg(io.StringIO(nfg_str))
+            efg_str = export_gambit(game)
+        return gbt.read_efg(io.StringIO(efg_str))
     except Exception:
         pass
 
-    # Fall back to EFG export
+    # Fall back to NFG export (works for normal-form games)
     try:
-        efg_str = export_gambit(game)
-        return gbt.read_efg(io.StringIO(efg_str))
+        nfg_str = pyspiel.game_to_nfg_string(game)
+        return gbt.read_nfg(io.StringIO(nfg_str))
     except Exception as exc:
         raise ValueError(
-            f"OpenSpiel game '{game_name}' could not be exported to NFG or EFG format."
+            f"OpenSpiel game '{game_name}' could not be exported to EFG or NFG format."
         ) from exc
 
 
diff --git a/tests/test_catalog.py b/tests/test_catalog.py
index 9492ae6cd..c25bd307d 100644
--- a/tests/test_catalog.py
+++ b/tests/test_catalog.py
@@ -224,21 +224,21 @@ def _setup_pyspiel_mock(
     return mock_ps, mock_export_fn
 
 
-def test_openspiel_load_nfg_success(monkeypatch):
-    """NFG export succeeds: catalog.load returns a valid Game."""
-    _setup_pyspiel_mock(monkeypatch, nfg_str=_MOCK_NFG)
-    game = gbt.catalog.load("open_spiel/matrix_rps")
+def test_openspiel_load_efg_success(monkeypatch):
+    """EFG export succeeds: catalog.load returns a valid Game."""
+    _setup_pyspiel_mock(monkeypatch, efg_str=_MOCK_EFG)
+    game = gbt.catalog.load("open_spiel/tiny_hanabi")
     assert isinstance(game, gbt.Game)
 
 
-def test_openspiel_load_efg_fallback(monkeypatch):
-    """NFG export fails, EFG export succeeds: catalog.load returns a valid Game."""
+def test_openspiel_load_nfg_fallback(monkeypatch):
+    """EFG export fails, NFG export succeeds: catalog.load returns a valid Game."""
     _setup_pyspiel_mock(
         monkeypatch,
-        nfg_raises=RuntimeError("nfg not supported"),
-        efg_str=_MOCK_EFG,
+        efg_raises=RuntimeError("efg not supported"),
+        nfg_str=_MOCK_NFG,
     )
-    game = gbt.catalog.load("open_spiel/tiny_hanabi")
+    game = gbt.catalog.load("open_spiel/matrix_rps")
     assert isinstance(game, gbt.Game)
 
 
@@ -257,11 +257,11 @@ def test_openspiel_load_game_not_found(monkeypatch):
 
 
 def test_openspiel_load_export_failure(monkeypatch):
-    """Both NFG and EFG exports fail: raises ValueError."""
+    """Both EFG and NFG exports fail: raises ValueError."""
     _setup_pyspiel_mock(
         monkeypatch,
-        nfg_raises=RuntimeError("nfg not supported"),
         efg_raises=RuntimeError("efg not supported"),
+        nfg_raises=RuntimeError("nfg not supported"),
     )
     with pytest.raises(ValueError, match="could not be exported"):
         gbt.catalog.load("open_spiel/matrix_rps")

From dffab1baf5e07fc036382b427acae43b7e9452f9 Mon Sep 17 00:00:00 2001
From: Ed Chalstrey <edwardchalstrey@gmail.com>
Date: Thu, 4 Jun 2026 11:03:57 +0100
Subject: [PATCH 09/12] feat: promote OpenSpiel loading to dedicated
 load_openspiel function with parameter support

---
 doc/catalog.rst                               | 13 +++++--
 doc/pygambit.api.rst                          |  1 +
 .../openspiel.ipynb                           |  6 +--
 src/pygambit/catalog.py                       | 39 +++++++++++++------
 tests/test_catalog.py                         | 21 ++++++----
 5 files changed, 54 insertions(+), 26 deletions(-)

diff --git a/doc/catalog.rst b/doc/catalog.rst
index 3b6551a99..dfb0875e2 100644
--- a/doc/catalog.rst
+++ b/doc/catalog.rst
@@ -14,15 +14,20 @@ Games from the OpenSpiel library are also available; see :ref:`Loading OpenSpiel
 .. rubric:: Loading OpenSpiel games
 
 Games from the `OpenSpiel <https://openspiel.readthedocs.io/en/latest/games.html>`_ library
-can be loaded dynamically using the ``open_spiel/`` prefix:
+can be loaded using :func:`pygambit.catalog.load_openspiel`:
 
 .. code-block:: python
 
-   pygambit.catalog.load("open_spiel/matrix_rps")
-   pygambit.catalog.load("open_spiel/tiny_hanabi")
+   pygambit.catalog.load_openspiel("matrix_rps")
+   pygambit.catalog.load_openspiel("tiny_hanabi")
+   pygambit.catalog.load_openspiel("blotto", params={"players": 2, "coins": 3, "fields": 2})
+
+The ``params`` argument is forwarded directly to ``pyspiel.load_game``; see the
+`OpenSpiel game list <https://openspiel.readthedocs.io/en/latest/games.html>`_ for
+available parameters per game.
 
 This requires ``open_spiel`` to be installed (``pip install open_spiel``;
-not available on Windows). The game is exported to NFG or EFG format on the fly
+not available on Windows). The game is exported to EFG or NFG format on the fly
 and loaded into Gambit. Not all OpenSpiel games can be exported; a
 :class:`ValueError` is raised for games that are incompatible with either format.
 See the :doc:`OpenSpiel interoperability tutorial <tutorials/interoperability_tutorials/openspiel>` for worked examples.
diff --git a/doc/pygambit.api.rst b/doc/pygambit.api.rst
index 7f8eea604..5841f02be 100644
--- a/doc/pygambit.api.rst
+++ b/doc/pygambit.api.rst
@@ -338,4 +338,5 @@ Catalog of games
    :toctree: api/
 
    load
+   load_openspiel
    games
diff --git a/doc/tutorials/interoperability_tutorials/openspiel.ipynb b/doc/tutorials/interoperability_tutorials/openspiel.ipynb
index eed31fa09..74ec53ae6 100644
--- a/doc/tutorials/interoperability_tutorials/openspiel.ipynb
+++ b/doc/tutorials/interoperability_tutorials/openspiel.ipynb
@@ -147,7 +147,7 @@
    "id": "045cf8dd",
    "metadata": {},
    "source": [
-    "Gambit's catalog module can load games from the OpenSpiel library directly (here we also add a title and action labels to make the output more interpretable):\n"
+    "Gambit's catalog module can load games from the OpenSpiel library using `gbt.catalog.load_openspiel`:\n"
    ]
   },
   {
@@ -157,7 +157,7 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "gbt_matrix_rps_game = gbt.catalog.load(\"open_spiel/matrix_rps\")\n",
+    "gbt_matrix_rps_game = gbt.catalog.load_openspiel(\"matrix_rps\")\n",
     "\n",
     "gbt_matrix_rps_game.title = \"Rock-Paper-Scissors\"\n",
     "\n",
@@ -458,7 +458,7 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "gbt_hanabi_game = gbt.catalog.load(\"open_spiel/tiny_hanabi\")\n",
+    "gbt_hanabi_game = gbt.catalog.load_openspiel(\"tiny_hanabi\")\n",
     "eqm = gbt.nash.lcp_solve(gbt_hanabi_game).equilibria[0]"
    ]
   },
diff --git a/src/pygambit/catalog.py b/src/pygambit/catalog.py
index f3fb17a4c..3d568e8ee 100644
--- a/src/pygambit/catalog.py
+++ b/src/pygambit/catalog.py
@@ -22,8 +22,6 @@
     ".efg": gbt.read_efg,
 }
 
-_OPENSPIEL_PREFIX = "open_spiel/"
-
 
 @contextlib.contextmanager
 def _suppress_c_stderr():
@@ -49,14 +47,34 @@ def _suppress_c_stderr():
         os.close(saved_fd)
 
 
-def _load_from_openspiel(game_name: str) -> gbt.Game:
+def load_openspiel(game_name: str, params: dict | None = None) -> gbt.Game:
     """
-    Load a game from the OpenSpiel library by name.
+    Load a game from the OpenSpiel library into Gambit.
+
+    Parameters
+    ----------
+    game_name : str
+        The short name of the OpenSpiel game (e.g. ``"matrix_rps"``,
+        ``"tiny_hanabi"``). Passed directly to ``pyspiel.load_game``.
+    params : dict, optional
+        Game parameters forwarded to ``pyspiel.load_game``
+        (e.g. ``{"players": 2, "coins": 3, "fields": 2}`` for ``"blotto"``).
+        See the `OpenSpiel game list
+        <https://openspiel.readthedocs.io/en/latest/games.html>`_ for
+        available parameters per game. Defaults to an empty dict.
+
+    Returns
+    -------
+    gbt.Game
+        The loaded game.
 
-    Tries NFG export first; falls back to EFG export via the
-    open_spiel.python.algorithms.gambit exporter. Raises ImportError
-    if open_spiel is not installed, ValueError if the game cannot be
-    exported to either format.
+    Raises
+    ------
+    ImportError
+        If ``open_spiel`` is not installed.
+    ValueError
+        If ``pyspiel.load_game`` fails, or if the game cannot be exported
+        to EFG or NFG format.
     """
     try:
         import pyspiel
@@ -68,7 +86,7 @@ def _load_from_openspiel(game_name: str) -> gbt.Game:
         ) from exc
 
     try:
-        game = pyspiel.load_game(game_name)
+        game = pyspiel.load_game(game_name, params or {})
     except Exception as exc:
         raise ValueError(f"Could not load OpenSpiel game '{game_name}': {exc}") from exc
 
@@ -113,9 +131,6 @@ def load(slug: str) -> gbt.Game:
     """
     slug = str(Path(slug)).replace("\\", "/")
 
-    if slug.startswith(_OPENSPIEL_PREFIX):
-        return _load_from_openspiel(slug[len(_OPENSPIEL_PREFIX):])
-
     # Try to load from file
     for suffix, reader in READERS.items():
         resource_path = _CATALOG_RESOURCE / f"{slug}{suffix}"
diff --git a/tests/test_catalog.py b/tests/test_catalog.py
index c25bd307d..15a03770f 100644
--- a/tests/test_catalog.py
+++ b/tests/test_catalog.py
@@ -225,20 +225,20 @@ def _setup_pyspiel_mock(
 
 
 def test_openspiel_load_efg_success(monkeypatch):
-    """EFG export succeeds: catalog.load returns a valid Game."""
+    """EFG export succeeds: load_openspiel returns a valid Game."""
     _setup_pyspiel_mock(monkeypatch, efg_str=_MOCK_EFG)
-    game = gbt.catalog.load("open_spiel/tiny_hanabi")
+    game = gbt.catalog.load_openspiel("tiny_hanabi")
     assert isinstance(game, gbt.Game)
 
 
 def test_openspiel_load_nfg_fallback(monkeypatch):
-    """EFG export fails, NFG export succeeds: catalog.load returns a valid Game."""
+    """EFG export fails, NFG export succeeds: load_openspiel returns a valid Game."""
     _setup_pyspiel_mock(
         monkeypatch,
         efg_raises=RuntimeError("efg not supported"),
         nfg_str=_MOCK_NFG,
     )
-    game = gbt.catalog.load("open_spiel/matrix_rps")
+    game = gbt.catalog.load_openspiel("matrix_rps")
     assert isinstance(game, gbt.Game)
 
 
@@ -246,14 +246,14 @@ def test_openspiel_load_import_error(monkeypatch):
     """Missing open_spiel raises ImportError with a helpful message."""
     monkeypatch.setitem(sys.modules, "pyspiel", None)
     with pytest.raises(ImportError, match="open_spiel"):
-        gbt.catalog.load("open_spiel/matrix_rps")
+        gbt.catalog.load_openspiel("matrix_rps")
 
 
 def test_openspiel_load_game_not_found(monkeypatch):
     """pyspiel.load_game failure raises ValueError."""
     _setup_pyspiel_mock(monkeypatch, load_raises=RuntimeError("unknown game"))
     with pytest.raises(ValueError, match="bogus_game"):
-        gbt.catalog.load("open_spiel/bogus_game")
+        gbt.catalog.load_openspiel("bogus_game")
 
 
 def test_openspiel_load_export_failure(monkeypatch):
@@ -264,4 +264,11 @@ def test_openspiel_load_export_failure(monkeypatch):
         nfg_raises=RuntimeError("nfg not supported"),
     )
     with pytest.raises(ValueError, match="could not be exported"):
-        gbt.catalog.load("open_spiel/matrix_rps")
+        gbt.catalog.load_openspiel("matrix_rps")
+
+
+def test_openspiel_load_with_params(monkeypatch):
+    """params dict is forwarded to pyspiel.load_game."""
+    mock_ps, _ = _setup_pyspiel_mock(monkeypatch, nfg_str=_MOCK_NFG)
+    gbt.catalog.load_openspiel("blotto", params={"players": 2, "coins": 3, "fields": 2})
+    mock_ps.load_game.assert_called_once_with("blotto", {"players": 2, "coins": 3, "fields": 2})

From b55a2b9da2d8b3f211a1f17786518bc0bf3df1ba Mon Sep 17 00:00:00 2001
From: Theodore Turocy <ted.turocy@gmail.com>
Date: Thu, 4 Jun 2026 12:22:28 +0100
Subject: [PATCH 10/12] Added ChangeLog, minor docstring tweak

---
 ChangeLog               | 3 +++
 src/pygambit/catalog.py | 2 +-
 2 files changed, 4 insertions(+), 1 deletion(-)

diff --git a/ChangeLog b/ChangeLog
index a50e9f412..879cf50d2 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -2,6 +2,9 @@
 
 ## [16.7.0] - unreleased
 
+### Added
+- Games can be materialised directly from OpenSpiel games if `pyspiel` is installed. (#917)
+
 ### Fixed
 - Corrected resizing of row and column index labels in strategic form so pivoting works correctly. (#844)
 - Corrected incorrect output of strategic game tables to .nfg files if strategies have previously been
diff --git a/src/pygambit/catalog.py b/src/pygambit/catalog.py
index 3d568e8ee..a5fee18de 100644
--- a/src/pygambit/catalog.py
+++ b/src/pygambit/catalog.py
@@ -49,7 +49,7 @@ def _suppress_c_stderr():
 
 def load_openspiel(game_name: str, params: dict | None = None) -> gbt.Game:
     """
-    Load a game from the OpenSpiel library into Gambit.
+    Load a game from the OpenSpiel library.
 
     Parameters
     ----------

From 6b53e362eaf4a930e655ffa227d8d2cf4e2627f3 Mon Sep 17 00:00:00 2001
From: Ed Chalstrey <edwardchalstrey@gmail.com>
Date: Thu, 4 Jun 2026 15:33:06 +0100
Subject: [PATCH 11/12] refactor: replace heuristic OpenSpiel export fallback
 with explicit dynamics-based selection and don't include OpenSpiel's own
 errors

---
 src/pygambit/catalog.py | 75 ++++++++++++++++-----------------------
 tests/test_catalog.py   | 77 ++++++++++++++++++++++++++++++-----------
 2 files changed, 86 insertions(+), 66 deletions(-)

diff --git a/src/pygambit/catalog.py b/src/pygambit/catalog.py
index a5fee18de..9eb03cb8c 100644
--- a/src/pygambit/catalog.py
+++ b/src/pygambit/catalog.py
@@ -1,6 +1,4 @@
-import contextlib
 import io
-import os
 from importlib.resources import as_file, files
 from pathlib import Path
 from typing import Any
@@ -23,30 +21,6 @@
 }
 
 
-@contextlib.contextmanager
-def _suppress_c_stderr():
-    """Redirect C-level stderr (fd 2) to /dev/null for the duration of the block.
-
-    This prevents OpenSpiel's C++ code from printing error messages (e.g.
-    "OpenSpiel exception: Must be a normal-form game") to the user's terminal or
-    notebook when we speculatively attempt an export that may not be supported.
-    Falls back silently if the fd-level redirect is unavailable (e.g. Windows).
-    """
-    try:
-        devnull_fd = os.open(os.devnull, os.O_WRONLY)
-        saved_fd = os.dup(2)
-        os.dup2(devnull_fd, 2)
-        os.close(devnull_fd)
-    except OSError:
-        yield
-        return
-    try:
-        yield
-    finally:
-        os.dup2(saved_fd, 2)
-        os.close(saved_fd)
-
-
 def load_openspiel(game_name: str, params: dict | None = None) -> gbt.Game:
     """
     Load a game from the OpenSpiel library.
@@ -73,8 +47,11 @@ def load_openspiel(game_name: str, params: dict | None = None) -> gbt.Game:
     ImportError
         If ``open_spiel`` is not installed.
     ValueError
-        If ``pyspiel.load_game`` fails, or if the game cannot be exported
-        to EFG or NFG format.
+        If the game's dynamics type is not supported for export, or if the
+        format exporter raises an error for this specific game.
+    Other exceptions from ``pyspiel.load_game`` propagate directly.
+        For example, ``pyspiel.SpielError`` is raised for unknown game names
+        or invalid/missing parameters.
     """
     try:
         import pyspiel
@@ -85,29 +62,37 @@ def load_openspiel(game_name: str, params: dict | None = None) -> gbt.Game:
             "Install it with: pip install open_spiel"
         ) from exc
 
-    try:
-        game = pyspiel.load_game(game_name, params or {})
-    except Exception as exc:
-        raise ValueError(f"Could not load OpenSpiel game '{game_name}': {exc}") from exc
+    # Let pyspiel's own exceptions propagate unchanged — they already carry
+    # informative messages ("Unknown game '...'", "Unknown parameter '...'", etc.)
+    game = pyspiel.load_game(game_name, params or {})
 
-    # Try EFG first (works for extensive-form games).
-    # Suppress C-level stderr so any C++ error messages for games that don't
-    # support EFG export are not shown when we fall through to the NFG path.
-    try:
-        with _suppress_c_stderr():
+    dynamics = game.get_type().dynamics
+
+    # OpenSpiel's SEQUENTIAL corresponds to extensive-form (tree) games in Gambit;
+    # SIMULTANEOUS corresponds to normal-form (strategic-form) games.
+    if dynamics == pyspiel.GameType.Dynamics.SEQUENTIAL:
+        try:
             efg_str = export_gambit(game)
+        except Exception as exc:
+            raise ValueError(
+                f"OpenSpiel game '{game_name}' could not be exported to EFG format: {exc}"
+            ) from exc
         return gbt.read_efg(io.StringIO(efg_str))
-    except Exception:
-        pass
 
-    # Fall back to NFG export (works for normal-form games)
-    try:
-        nfg_str = pyspiel.game_to_nfg_string(game)
+    elif dynamics == pyspiel.GameType.Dynamics.SIMULTANEOUS:
+        try:
+            nfg_str = pyspiel.game_to_nfg_string(game)
+        except Exception as exc:
+            raise ValueError(
+                f"OpenSpiel game '{game_name}' could not be exported to NFG format: {exc}"
+            ) from exc
         return gbt.read_nfg(io.StringIO(nfg_str))
-    except Exception as exc:
+
+    else:
         raise ValueError(
-            f"OpenSpiel game '{game_name}' could not be exported to EFG or NFG format."
-        ) from exc
+            f"OpenSpiel game '{game_name}' has unsupported dynamics type "
+            f"'{dynamics}' and cannot be exported to Gambit format."
+        )
 
 
 def load(slug: str) -> gbt.Game:
diff --git a/tests/test_catalog.py b/tests/test_catalog.py
index 15a03770f..f019d4a01 100644
--- a/tests/test_catalog.py
+++ b/tests/test_catalog.py
@@ -193,15 +193,34 @@ def _setup_pyspiel_mock(
     efg_str=None,
     efg_raises=None,
     load_raises=None,
+    dynamics="sequential",
 ):
-    """Inject a fake pyspiel + open_spiel.python.algorithms.gambit into sys.modules."""
+    """Inject a fake pyspiel + open_spiel.python.algorithms.gambit into sys.modules.
+
+    ``dynamics`` controls which export path the code takes:
+    - ``"sequential"`` → game.get_type().dynamics == pyspiel.GameType.Dynamics.SEQUENTIAL
+      (OpenSpiel's term for extensive-form / tree games in Gambit)
+    - ``"simultaneous"`` → SIMULTANEOUS (normal-form / strategic-form games in Gambit)
+    - ``"other"`` → any other value, triggers the unsupported-dynamics ValueError
+    """
     mock_ps = MagicMock()
     mock_export_fn = MagicMock()
+    mock_game = MagicMock()
+
+    # Wire the dynamics attribute so the == comparison in load_openspiel resolves correctly.
+    # MagicMock attribute access is idempotent: mock_ps.GameType.Dynamics.SEQUENTIAL always
+    # returns the same object, so the equality check passes.
+    if dynamics == "sequential":
+        mock_game.get_type.return_value.dynamics = mock_ps.GameType.Dynamics.SEQUENTIAL
+    elif dynamics == "simultaneous":
+        mock_game.get_type.return_value.dynamics = mock_ps.GameType.Dynamics.SIMULTANEOUS
+    else:
+        mock_game.get_type.return_value.dynamics = object()  # matches neither branch
 
     if load_raises is not None:
         mock_ps.load_game.side_effect = load_raises
     else:
-        mock_ps.load_game.return_value = MagicMock()
+        mock_ps.load_game.return_value = mock_game
 
     if nfg_raises is not None:
         mock_ps.game_to_nfg_string.side_effect = nfg_raises
@@ -225,19 +244,15 @@ def _setup_pyspiel_mock(
 
 
 def test_openspiel_load_efg_success(monkeypatch):
-    """EFG export succeeds: load_openspiel returns a valid Game."""
-    _setup_pyspiel_mock(monkeypatch, efg_str=_MOCK_EFG)
+    """Sequential (extensive-form) game: EFG export is used and returns a valid Game."""
+    _setup_pyspiel_mock(monkeypatch, dynamics="sequential", efg_str=_MOCK_EFG)
     game = gbt.catalog.load_openspiel("tiny_hanabi")
     assert isinstance(game, gbt.Game)
 
 
-def test_openspiel_load_nfg_fallback(monkeypatch):
-    """EFG export fails, NFG export succeeds: load_openspiel returns a valid Game."""
-    _setup_pyspiel_mock(
-        monkeypatch,
-        efg_raises=RuntimeError("efg not supported"),
-        nfg_str=_MOCK_NFG,
-    )
+def test_openspiel_load_nfg_success(monkeypatch):
+    """Simultaneous (normal-form) game: NFG export is used and returns a valid Game."""
+    _setup_pyspiel_mock(monkeypatch, dynamics="simultaneous", nfg_str=_MOCK_NFG)
     game = gbt.catalog.load_openspiel("matrix_rps")
     assert isinstance(game, gbt.Game)
 
@@ -250,25 +265,45 @@ def test_openspiel_load_import_error(monkeypatch):
 
 
 def test_openspiel_load_game_not_found(monkeypatch):
-    """pyspiel.load_game failure raises ValueError."""
-    _setup_pyspiel_mock(monkeypatch, load_raises=RuntimeError("unknown game"))
-    with pytest.raises(ValueError, match="bogus_game"):
+    """pyspiel.load_game errors propagate directly without wrapping."""
+    _setup_pyspiel_mock(monkeypatch, load_raises=RuntimeError("Unknown game 'bogus_game'"))
+    with pytest.raises(RuntimeError, match="Unknown game"):
         gbt.catalog.load_openspiel("bogus_game")
 
 
-def test_openspiel_load_export_failure(monkeypatch):
-    """Both EFG and NFG exports fail: raises ValueError."""
+def test_openspiel_load_efg_export_failure(monkeypatch):
+    """EFG export failure on a sequential game raises ValueError with format context."""
+    _setup_pyspiel_mock(
+        monkeypatch,
+        dynamics="sequential",
+        efg_raises=RuntimeError("export error"),
+    )
+    with pytest.raises(ValueError, match="EFG format"):
+        gbt.catalog.load_openspiel("tiny_hanabi")
+
+
+def test_openspiel_load_nfg_export_failure(monkeypatch):
+    """NFG export failure on a simultaneous game raises ValueError with format context."""
     _setup_pyspiel_mock(
         monkeypatch,
-        efg_raises=RuntimeError("efg not supported"),
-        nfg_raises=RuntimeError("nfg not supported"),
+        dynamics="simultaneous",
+        nfg_raises=RuntimeError("export error"),
     )
-    with pytest.raises(ValueError, match="could not be exported"):
+    with pytest.raises(ValueError, match="NFG format"):
         gbt.catalog.load_openspiel("matrix_rps")
 
 
+def test_openspiel_load_unsupported_dynamics(monkeypatch):
+    """A game with unsupported dynamics (e.g. MEAN_FIELD) raises ValueError."""
+    _setup_pyspiel_mock(monkeypatch, dynamics="other")
+    with pytest.raises(ValueError, match="unsupported dynamics"):
+        gbt.catalog.load_openspiel("some_mfg_game")
+
+
 def test_openspiel_load_with_params(monkeypatch):
-    """params dict is forwarded to pyspiel.load_game."""
-    mock_ps, _ = _setup_pyspiel_mock(monkeypatch, nfg_str=_MOCK_NFG)
+    """params dict is forwarded verbatim to pyspiel.load_game."""
+    mock_ps, _ = _setup_pyspiel_mock(
+        monkeypatch, dynamics="simultaneous", nfg_str=_MOCK_NFG
+    )
     gbt.catalog.load_openspiel("blotto", params={"players": 2, "coins": 3, "fields": 2})
     mock_ps.load_game.assert_called_once_with("blotto", {"players": 2, "coins": 3, "fields": 2})

From 68a7857d8a4d75400c11a26751012f6af6db3caa Mon Sep 17 00:00:00 2001
From: Ted Turocy <ted.turocy@gmail.com>
Date: Fri, 5 Jun 2026 09:18:50 +0100
Subject: [PATCH 12/12] Update catalog.py

---
 src/pygambit/catalog.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/pygambit/catalog.py b/src/pygambit/catalog.py
index 9eb03cb8c..2b6aadaeb 100644
--- a/src/pygambit/catalog.py
+++ b/src/pygambit/catalog.py
@@ -35,7 +35,7 @@ def load_openspiel(game_name: str, params: dict | None = None) -> gbt.Game:
         (e.g. ``{"players": 2, "coins": 3, "fields": 2}`` for ``"blotto"``).
         See the `OpenSpiel game list
         <https://openspiel.readthedocs.io/en/latest/games.html>`_ for
-        available parameters per game. Defaults to an empty dict.
+        available parameters per game.
 
     Returns
     -------