diff --git a/tests/test_futoshiki.py b/tests/test_futoshiki.py
new file mode 100644
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+++ b/tests/test_futoshiki.py
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+import pytest
+
+from reasoning_gym.games import FutoshikiConfig, FutoshikiDataset
+
+
+def test_futoshiki_config_validation():
+    """Test that invalid configs raise appropriate errors"""
+    with pytest.raises(AssertionError):
+        config = FutoshikiConfig(board_size=3)  # Too small
+        config.validate()
+
+    with pytest.raises(AssertionError):
+        config = FutoshikiConfig(board_size=10)  # Too large
+        config.validate()
+
+    with pytest.raises(AssertionError):
+        config = FutoshikiConfig(difficulty=-1)  # Invalid difficulty
+        config.validate()
+
+    with pytest.raises(AssertionError):
+        config = FutoshikiConfig(difficulty=4)  # Invalid difficulty
+        config.validate()
+
+
+def test_futoshiki_deterministic():
+    """Test that dataset generates same puzzles with same seed"""
+    config = FutoshikiConfig(seed=42, size=10)
+    dataset1 = FutoshikiDataset(config)
+    dataset2 = FutoshikiDataset(config)
+
+    for i in range(len(dataset1)):
+        assert dataset1[i] == dataset2[i]
+
+
+def test_futoshiki_items():
+    """Test basic properties of generated items"""
+    config = FutoshikiConfig(board_size=4, difficulty=1, size=10, seed=42)
+    dataset = FutoshikiDataset(config)
+
+    for i in range(len(dataset)):
+        item = dataset[i]
+        assert isinstance(item, dict)
+        assert "question" in item
+        assert "answer" in item
+        assert "metadata" in item
+
+        # Verify metadata contents
+        metadata = item["metadata"]
+        assert "puzzle" in metadata
+        assert "solution" in metadata
+        assert "constraints" in metadata
+        assert "board_size" in metadata
+        assert "difficulty" in metadata
+
+        # Verify board dimensions
+        puzzle = metadata["puzzle"]
+        solution = metadata["solution"]
+        assert len(puzzle) == config.board_size
+        assert len(solution) == config.board_size
+        for row in puzzle:
+            assert len(row) == config.board_size
+        for row in solution:
+            assert len(row) == config.board_size
+
+        # Verify constraints format
+        constraints = metadata["constraints"]
+        for ((r1, c1), (r2, c2)), rel in constraints.items():
+            assert 0 <= r1 < config.board_size
+            assert 0 <= c1 < config.board_size
+            assert 0 <= r2 < config.board_size
+            assert 0 <= c2 < config.board_size
+            assert rel in ("<", ">")
+
+
+def test_futoshiki_solution_validity():
+    """Test that solutions are valid according to Futoshiki rules"""
+    config = FutoshikiConfig(board_size=4, difficulty=1, size=10, seed=42)
+    dataset = FutoshikiDataset(config)
+
+    def is_valid_solution(solution, board_size, constraints):
+        # Check rows
+        for row in solution:
+            if sorted(row) != list(range(1, board_size + 1)):
+                return False
+
+        # Check columns
+        for col in range(board_size):
+            column = [solution[row][col] for row in range(board_size)]
+            if sorted(column) != list(range(1, board_size + 1)):
+                return False
+
+        # Check constraints
+        for ((r1, c1), (r2, c2)), rel in constraints.items():
+            v1, v2 = solution[r1][c1], solution[r2][c2]
+            if rel == "<" and not (v1 < v2):
+                return False
+            if rel == ">" and not (v1 > v2):
+                return False
+
+        return True
+
+    for i in range(len(dataset)):
+        item = dataset[i]
+        metadata = item["metadata"]
+        solution = metadata["solution"]
+        constraints = metadata["constraints"]
+
+        assert is_valid_solution(solution, config.board_size, constraints)
+
+
+def test_futoshiki_puzzle_solvability():
+    """Test that generated puzzles are solvable and have unique solutions"""
+    config = FutoshikiConfig(board_size=4, difficulty=1, size=5, seed=42)
+    dataset = FutoshikiDataset(config)
+
+    for i in range(len(dataset)):
+        item = dataset[i]
+        metadata = item["metadata"]
+        puzzle = metadata["puzzle"]
+        constraints = metadata["constraints"]
+
+        # Verify puzzle has exactly one solution
+        assert dataset.count_solutions(puzzle, constraints, limit=2) == 1
+
+
+def test_futoshiki_difficulty_levels():
+    """Test that different difficulty levels affect puzzle complexity"""
+    size = 5
+    board_size = 4
+    seeds = [42, 43, 44]  # Test multiple seeds for robustness
+
+    def count_clues(puzzle):
+        return sum(cell != 0 for row in puzzle for cell in row)
+
+    def count_constraints(constraints):
+        return len(constraints)
+
+    for seed in seeds:
+        clues_by_difficulty = []
+        constraints_by_difficulty = []
+
+        for difficulty in range(4):  # 0 to 3
+            config = FutoshikiConfig(board_size=board_size, difficulty=difficulty, size=size, seed=seed)
+            dataset = FutoshikiDataset(config)
+
+            avg_clues = sum(count_clues(item["metadata"]["puzzle"]) for item in dataset) / size
+            avg_constraints = sum(count_constraints(item["metadata"]["constraints"]) for item in dataset) / size
+
+            clues_by_difficulty.append(avg_clues)
+            constraints_by_difficulty.append(avg_constraints)
+
+        # Higher difficulty should generally mean fewer clues and/or more constraints
+        assert all(clues_by_difficulty[i] >= clues_by_difficulty[i + 1] for i in range(len(clues_by_difficulty) - 1))
+        assert all(
+            constraints_by_difficulty[i] <= constraints_by_difficulty[i + 1]
+            for i in range(len(constraints_by_difficulty) - 1)
+        )
+
+
+def test_futoshiki_answer_scoring():
+    """Test the answer scoring mechanism"""
+    config = FutoshikiConfig(board_size=4, difficulty=0, size=5, seed=42)
+    dataset = FutoshikiDataset(config)
+
+    item = dataset[0]
+
+    # Correct answer should score 1.0
+    assert dataset.score_answer(item["answer"], item) == 1.0
+
+    # Wrong answer should score lower
+    wrong_answer = item["answer"].replace("1", "2")
+    assert dataset.score_answer(wrong_answer, item) < 1.0
+
+    # None or empty answer should score 0.0
+    assert dataset.score_answer(None, item) == 0.0
+    assert dataset.score_answer("", item) == 0.01