Add pause option to play to allow turn based games (#1042)

gymnasium/utils/play.py

@@ -154,9 +154,12 @@ def play(
     keys_to_action: dict[tuple[str | int, ...] | str | int, ActType] | None = None,
     seed: int | None = None,
     noop: ActType = 0,
+    wait_on_player: bool = False,
 ):
     """Allows the user to play the environment using a keyboard.
 
+    If playing in a turn-based environment, set wait_on_player to True.
+
     Args:
         env: Environment to use for playing.
         transpose: If this is ``True``, the output of observation is transposed. Defaults to ``True``.
@@ -204,6 +207,7 @@ def play(
             If ``None``, default ``key_to_action`` mapping for that environment is used, if provided.
         seed: Random seed used when resetting the environment. If None, no seed is used.
         noop: The action used when no key input has been entered, or the entered key combination is unknown.
+        wait_on_player: Play should wait for a user action
 
     Example:
         >>> import gymnasium as gym
@@ -283,7 +287,7 @@ def play(
         if done:
             done = False
             obs = env.reset(seed=seed)
-        else:
+        elif wait_on_player is False or len(game.pressed_keys) > 0:
             action = key_code_to_action.get(tuple(sorted(game.pressed_keys)), noop)
             prev_obs = obs
             obs, rew, terminated, truncated, info = env.step(action)