diff --git a/assets/src/ba_data/python/ba/_activity.py b/assets/src/ba_data/python/ba/_activity.py
index d06e3dc2..b19a2e40 100644
--- a/assets/src/ba_data/python/ba/_activity.py
+++ b/assets/src/ba_data/python/ba/_activity.py
@@ -113,7 +113,7 @@ class Activity(DependencyComponent, Generic[PlayerType, TeamType]):
     inherits_tint = False
 
     # Whether players should be allowed to join in the middle of
-    # activities.
+    # activity.
     allow_mid_activity_joins: bool = True
 
     # If the activity fades or transitions in, it should set the length of
diff --git a/assets/src/ba_data/python/ba/_coopgame.py b/assets/src/ba_data/python/ba/_coopgame.py
index f7c3dc07..1811bb05 100644
--- a/assets/src/ba_data/python/ba/_coopgame.py
+++ b/assets/src/ba_data/python/ba/_coopgame.py
@@ -27,8 +27,6 @@ class CoopGameActivity(GameActivity[PlayerType, TeamType]):
     # We can assume our session is a CoopSession.
     session: ba.CoopSession
 
-    allow_mid_activity_joins = False
-
     @classmethod
     def supports_session_type(cls, sessiontype: Type[ba.Session]) -> bool:
         from ba._coopsession import CoopSession
diff --git a/assets/src/ba_data/python/ba/_coopsession.py b/assets/src/ba_data/python/ba/_coopsession.py
index c6674c61..fed532e9 100644
--- a/assets/src/ba_data/python/ba/_coopsession.py
+++ b/assets/src/ba_data/python/ba/_coopsession.py
@@ -90,6 +90,16 @@ class CoopSession(Session):
         """Get the game instance currently being played."""
         return self._current_game_instance
 
+    def should_allow_mid_activity_joins(self, activity: Activity) -> bool:
+        # pylint: disable=cyclic-import
+        from ba._gameactivity import GameActivity
+
+        # Disallow any joins in the middle of the game.
+        if isinstance(activity, GameActivity):
+            return False
+
+        return True
+
     def _update_on_deck_game_instances(self) -> None:
         # pylint: disable=cyclic-import
         from ba._gameactivity import GameActivity
diff --git a/assets/src/ba_data/python/ba/_session.py b/assets/src/ba_data/python/ba/_session.py
index 6ff90754..2c7e6520 100644
--- a/assets/src/ba_data/python/ba/_session.py
+++ b/assets/src/ba_data/python/ba/_session.py
@@ -205,6 +205,14 @@ class Session:
             raise NodeNotFoundError()
         return node
 
+    def should_allow_mid_activity_joins(self, activity: Activity) -> bool:
+        """Returned value is used by the Session to determine
+        whether to allow players to join in the middle of activity.
+
+        Activity.allow_mid_activity_joins is also required to allow these
+        joins."""
+        return True
+
     def on_player_request(self, player: ba.SessionPlayer) -> bool:
         """Called when a new ba.Player wants to join the Session.
 
@@ -651,7 +659,8 @@ class Session:
         # However, if we're not allowing mid-game joins, don't actually pass;
         # just announce the arrival and say they'll partake next round.
         if pass_to_activity:
-            if not activity.allow_mid_activity_joins:
+            if not (activity.allow_mid_activity_joins
+                    and self.should_allow_mid_activity_joins(activity)):
                 pass_to_activity = False
                 with _ba.Context(self):
                     _ba.screenmessage(
diff --git a/assets/src/ba_data/python/bastd/game/meteorshower.py b/assets/src/ba_data/python/bastd/game/meteorshower.py
index 9be79902..32c62c0d 100644
--- a/assets/src/ba_data/python/bastd/game/meteorshower.py
+++ b/assets/src/ba_data/python/bastd/game/meteorshower.py
@@ -44,7 +44,11 @@ class MeteorShowerGame(ba.TeamGameActivity[Player, Team]):
     # Print messages when players die (since its meaningful in this game).
     announce_player_deaths = True
 
-    # we're currently hard-coded for one map..
+    # Don't allow joining after we start
+    # (would enable leave/rejoin tomfoolery).
+    allow_mid_activity_joins = False
+
+    # We're currently hard-coded for one map.
     @classmethod
     def get_supported_maps(cls, sessiontype: Type[ba.Session]) -> List[str]:
         return ['Rampage']
@@ -93,22 +97,6 @@ class MeteorShowerGame(ba.TeamGameActivity[Player, Team]):
         # Check for immediate end (if we've only got 1 player, etc).
         ba.timer(5.0, self._check_end_game)
 
-    def on_player_join(self, player: Player) -> None:
-        # Don't allow joining after we start
-        # (would enable leave/rejoin tomfoolery).
-        if self.has_begun():
-            ba.screenmessage(
-                ba.Lstr(resource='playerDelayedJoinText',
-                        subs=[('${PLAYER}', player.getname(full=True))]),
-                color=(0, 1, 0),
-            )
-            # For score purposes, mark them as having died right as the
-            # game started.
-            assert self._timer is not None
-            player.death_time = self._timer.getstarttime()
-            return
-        self.spawn_player(player)
-
     def on_player_leave(self, player: Player) -> None:
         # Augment default behavior.
         super().on_player_leave(player)