Update example game some, update engine some

* Add RevealAction/UnrevealAction for revealing/hiding items in a room
* Add a lot of checks for items being revealed when it's attempted to be
  triggered
* Implement TeleportAction (mostly)
* For all Check* family of actions, the `yes` and `no` values may be
  just be a single action instead of an array of actions
* Change up how room descriptions and stuff work, mostly so that you can
  specify multiple lines in an array so you can preserve paragraph
  breaks when displayed.
* Example game has some more content

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

agame/action.py

@@ -19,6 +19,8 @@ __all__ = (
     "Var",
     "CheckVarAction",
     "SetVarAction",
+    "RevealItemAction",
+    "UnrevealItemAction",
 )
 
 
@@ -79,8 +81,10 @@ class TeleportAction(Action):
     room_id: str
 
     def act(self, game: "Game"):
-        # TODO
-        raise NotImplementedError("TODO - implement teleport action")
+        assert (
+            self.room_id in game.database.rooms
+        ), f"could not find room with id {self.room_id}"
+        game.room = game.database.rooms[self.room_id]
 
 
 @dataclasses.dataclass
@@ -126,6 +130,24 @@ class CheckInvItemsAction(Action):
     yes: Sequence[Action]
     no: Sequence[Action]
 
+    def __init__(
+        self,
+        item_ids: Union[str, Sequence[str]],
+        yes: Union[Action, Sequence[Action]] = [],
+        no: Union[Action, Sequence[Action]] = [],
+    ):
+        self.item_ids = item_ids
+        # Put the "yes" action into an array if necessary
+        if isinstance(yes, Action):
+            self.yes = [yes]
+        else:
+            self.yes = yes
+        # Put the "no" action into an array if necessary
+        if isinstance(no, Action):
+            self.no = [no]
+        else:
+            self.no = no
+
     def act(self, game: "Game"):
         # If the item_ids are just a string, use that as a list.
         items = [self.item_ids] if isinstance(self.item_ids, str) else self.item_ids
@@ -143,10 +165,28 @@ class CheckRoomItemsAction(Action):
     appropriate action sequence.
     """
 
-    item_ids: str
+    item_ids: Union[str, Sequence[str]]
     yes: Sequence[Action]
     no: Sequence[Action]
 
+    def __init__(
+        self,
+        item_ids: Union[str, Sequence[str]],
+        yes: Union[Action, Sequence[Action]] = [],
+        no: Union[Action, Sequence[Action]] = [],
+    ):
+        self.item_ids = item_ids
+        # Put the "yes" action into an array if necessary
+        if isinstance(yes, Action):
+            self.yes = [yes]
+        else:
+            self.yes = yes
+        # Put the "no" action into an array if necessary
+        if isinstance(no, Action):
+            self.no = [no]
+        else:
+            self.no = no
+
     def act(self, game: "Game"):
         items = [self.item_ids] if isinstance(self.item_ids, str) else self.item_ids
         for item_id in items:
@@ -225,10 +265,37 @@ class CheckVarAction(Action):
     # The action to execute when this is false.
     no: Sequence[Action]
 
+    def __init__(
+        self,
+        var_id: str,
+        compare: Compare = Compare.EQUALS,
+        against: Any = True,
+        yes: Union[Action, Sequence[Action]] = [],
+        no: Union[Action, Sequence[Action]] = [],
+    ):
+        self.var_id = var_id
+        self.compare = compare
+        self.against = against
+        # Put the "yes" action into an array if necessary
+        if isinstance(yes, Action):
+            self.yes = [yes]
+        else:
+            self.yes = yes
+        # Put the "no" action into an array if necessary
+        if isinstance(no, Action):
+            self.no = [no]
+        else:
+            self.no = no
+
     def act(self, game: "Game"):
+        assert self.var_id in game.vars, f"variable '{self.var_id}' does not exist"
+
         val = game.vars.get(self.var_id, None)
         compare_val = None
         if isinstance(self.against, Var):
+            assert (
+                self.against.id in game.vars
+            ), f"variable '{self.against.id}' does not exist"
             compare_val = game.vars.get(self.against.id, None)
         else:
             compare_val = self.against
@@ -288,7 +355,38 @@ class SetVarAction(Action):
     value: Any
 
     def act(self, game: "Game"):
+        assert self.var_id in game.vars, f"variable '{self.var_id}' does not exist"
         value = (
             game.vars.get(self.value.id) if isinstance(self.value, Var) else self.value
         )
         game.vars[self.var_id] = value
+
+
+@dataclasses.dataclass
+class RevealItemAction(Action):
+    """
+    Reveal an item in the current room.
+    """
+
+    item_id: str
+
+    def act(self, game: "Game"):
+        assert (
+            self.item_id in game.room.items
+        ), f"item id {self.item_id} does not exist in the current room {game.room.id}"
+        game.room.items[self.item_id].revealed = True
+
+
+@dataclasses.dataclass
+class UnrevealItemAction(Action):
+    """
+    Unreveal an item in the current room.
+    """
+
+    item_id: str
+
+    def act(self, game: "Game"):
+        assert (
+            self.item_id in game.room.items
+        ), f"item id {self.item_id} does not exist in the current room {game.room.id}"
+        game.room.items[self.item_id].revealed = False