--- a/gamelib/game_base.py	Wed May 09 21:16:53 2012 +0200
+++ b/gamelib/game_base.py	Wed May 09 21:22:10 2012 +0200
@@ -8,6 +8,8 @@
         if leaf_only and cls.__subclasses__():
             # Not a leaf class, and only want leaves
             continue
+        if hasattr(cls, 'sanity_check'):
+            cls.sanity_check()
         subclasses.append(cls)
     return subclasses
 
@@ -60,3 +62,9 @@
 
     def save_data(self):
         return (self.save_name(), self.points)
+
+    @classmethod
+    def sanity_check(cls):
+        for science, points in cls.PREREQUISITES:
+            assert issubclass(science, Science)
+            assert isinstance(points, int)