diff --git a/antisplice.cabal b/antisplice.cabal
--- a/antisplice.cabal
+++ b/antisplice.cabal
@@ -10,7 +10,7 @@
 -- PVP summary:      +-+------- breaking API changes
 --                   | | +----- non-breaking API additions
 --                   | | | +--- code changes with no API change
-version:             0.13.1.0
+version:             0.13.2.0
 
 -- A short (one-line) description of the package.
 synopsis:            An engine for text-based dungeons.
diff --git a/src/Game/Antisplice/Monad/Dungeon.hs b/src/Game/Antisplice/Monad/Dungeon.hs
--- a/src/Game/Antisplice/Monad/Dungeon.hs
+++ b/src/Game/Antisplice/Monad/Dungeon.hs
@@ -44,6 +44,7 @@
     Relation (..),
     Feature (..),
     ObjectId (..),
+    KindId (..),
     ObjectState (..),
     ObjectT (..),
     MonadObject (..),
@@ -219,8 +220,13 @@
 -- | Phantom ID type for objects.
 data ObjectId = ObjectId Int | FalseObject deriving (Eq,Ord)
 
+-- | Phantom ID type for object kinds.
+data KindId = KindId Int | FalseKind deriving (Eq,Ord)
+
 instance None ObjectId where
   none = FalseObject
+instance None KindId where
+  none = FalseKind
 
 -- | Target for attacks. May be a player or an object.
 data DamageTarget = TargetPlayer PlayerId | TargetObject ObjectId
@@ -228,6 +234,7 @@
 -- | State type for ObjectT
 data ObjectState = ObjectState {
     objectIdOf :: !ObjectId,
+    objectKindOf :: !KindId,
     objectTitleOf :: !Text,
     objectDescOf :: !Text,
     objectNamesOf :: ![String],
diff --git a/src/Game/Antisplice/Rooms.hs b/src/Game/Antisplice/Rooms.hs
--- a/src/Game/Antisplice/Rooms.hs
+++ b/src/Game/Antisplice/Rooms.hs
@@ -41,6 +41,7 @@
     removeRoomObject,
     insertRoomObject,
     -- * Object construction
+    constructObject,
     modifyObjectState,
     setObjectDesc,
     setObjectTitle,
@@ -54,6 +55,8 @@
     -- * Object forms
     registerForm,
     instanciateForm,
+    registerKind,
+    setObjectKind,
     -- * Object investigation
     getObjectTitle,
     getObjectDesc,
@@ -77,6 +80,8 @@
     getEquipment,
     getCooldown,
     setCooldown,
+    -- * Currencies
+    registerCurrency,
     getCurrency,
     modifyCurrency,
     -- * Fight
@@ -90,7 +95,10 @@
     -- * Guardians
     guardRoom,
     guardObject,
-    guardObjectInRoom
+    guardObjectInRoom,
+    guardObjectNotInRoom,
+    guardKindInRoom,
+    guardKindNotInRoom
   ) where
 
 import Text.Chatty.Printer
@@ -232,15 +240,17 @@
 addRoomObject :: (MonadCounter m,MonadRoom m) => ObjectT m a -> m ObjectId
 addRoomObject m = do
   i <- liftM ObjectId countOn
-  o <- constructObject m $ Just i
+  k <- liftM KindId countOn
+  o <- constructObject m (Just i) k
   insertRoomObject o
   return i
 
 -- | Construct a room object (but don't add it)
-constructObject :: Monad m => ObjectT m a -> Maybe ObjectId -> m ObjectState
-constructObject m j = do
+constructObject :: Monad m => ObjectT m a -> Maybe ObjectId -> KindId -> m ObjectState
+constructObject m j k = do
   (_,o) <- runObjectT m $ ObjectState
        (if isJust j then (\(Just j) -> j) j else none) -- id
+       k -- kid
        (pack "Something") -- title
        (pack "I don't know what this is.") -- desc
        none none False False False False -- names, attr, 1seen?, 1acq?, 1insp?, 1eq?
@@ -345,10 +355,18 @@
 
 -- | Set whether the current object is a mob.
 setObjectIsMob :: MonadObject m => Bool -> m ()
-setObjectIsMob b = modifyObjectState $ \o -> o{objectFeaturesOf=a b $ objectFeaturesOf o}
-  where a True = avlInsert Mobile
-        a False = avlRemove Mobile
+setObjectIsMob b = modifyObjectState $ \o -> o{objectFeaturesOf=a b Mobile $ objectFeaturesOf o}
+  where a True = avlInsert
+        a False = avlRemove
 
+-- | Set object kind.
+setObjectKind :: MonadObject m => KindId -> m ()
+setObjectKind k = modifyObjectState $ \o -> o{objectKindOf=k}
+
+-- | Register an object kind.
+registerKind :: MonadCounter m => m KindId
+registerKind = liftM KindId countOn
+
 -- | Check if the current object is acquirable.
 getObjectIsAcquirable :: (MonadObject m,Functor m) => m Bool
 getObjectIsAcquirable = fmap (isJust . avlLookup Acquirable . objectFeaturesOf) getObjectState
@@ -407,6 +425,28 @@
     [r1] | r1 == r -> m
     _ -> return ()
 
+-- | Only run the given function if the given object is not in the also given room
+guardObjectNotInRoom :: MonadDungeon m => ObjectId -> NodeId -> m () -> m ()
+guardObjectNotInRoom o r m = do
+  rs <- roomOfObject o
+  case rs of
+    [r1] | r1 == r -> return ()
+    _ -> m
+
+-- | Only run the given function if an object of the given kind is in the also given room
+guardKindInRoom :: MonadDungeon m => KindId -> NodeId -> m () -> m ()
+guardKindInRoom k r m = do
+  rs <- withRoom r getRoomState
+  let b = null $ filter ((==k).objectKindOf) $ avlPreorder $ roomObjectsOf rs
+  unless b m
+
+-- | Only run the given function if no object of the given kind is in the also given room
+guardKindNotInRoom :: MonadDungeon m => KindId -> NodeId -> m () -> m ()
+guardKindNotInRoom k r m = do
+  rs <- withRoom r getRoomState
+  let b = null $ filter ((==k).objectKindOf) $ avlPreorder $ roomObjectsOf rs
+  when b m
+
 -- | Determine which rooms contain the given object (won't be more than one, but we're careful)
 roomOfObject :: MonadDungeon m => ObjectId -> m [NodeId]
 roomOfObject o = (return . map nodeId . filter (isJust . avlLookup o . roomObjectsOf . nodeContent) . allNodes . roomsOf) =<< getDungeonState
@@ -422,6 +462,7 @@
         then do
           o <- withRoom r $ removeRoomObject i
           modifyPlayerState $ \s -> s{playerInventoryOf=avlInsert o $ playerInventoryOf s}
+          objectTriggerOnEachAcquireOf o
         else throwError CantAcquireThatError
     [] -> throwError CantSeeOneError
     _ -> throwError WhichOneError
@@ -450,7 +491,8 @@
 registerForm :: (MonadAtoms m) => ObjectT m () -> m (Atom ObjectState)
 registerForm m = do
   a <- newAtom
-  o <- constructObject m Nothing
+  k <- liftM KindId countOn
+  o <- constructObject m Nothing k
   putAtom a o
   return a
 
@@ -512,6 +554,14 @@
 modifyCurrency c f = modifyPlayerState $ \p ->
   let c1 = joinMaybe $ avlLookup c $ playerCurrenciesOf p
   in p{playerCurrenciesOf=avlInsert (c,f c1) $ playerCurrenciesOf p}
+
+-- | Register a currency
+registerCurrency :: (MonadCounter m,MonadDungeon m) => String -> String -> m CurrencyId
+registerCurrency n d = do
+  s <- getDungeonState
+  i <- liftM CurrencyId countOn
+  putDungeonState s{currenciesOf=avlInsert (Currency i d n) $ currenciesOf s}
+  return i
 
 -- | Run a function in the context of a given player
 withPlayer :: MonadDungeon m => PlayerId -> PlayerT (RoomT m) a -> m a