--- a/gamelib/gamestate.py	Mon May 07 00:27:59 2012 +0200
+++ b/gamelib/gamestate.py	Mon May 07 13:59:50 2012 +0200
@@ -41,9 +41,7 @@
 
     def get_available_missions(self):
         """Return a list of missions we can feasibly attempt"""
-        available = [x for x in self.missions
-                     if (x.MINIMUM_REPUTATION is None
-                         or x.MINIMUM_REPUTATION <= self.reputation)]
+        available = [x for x in self.missions if x.can_attempt(self)]
         return available
 
     def end_turn(self):
@@ -51,9 +49,6 @@
         mission_results = []
         for mission, equipment in self.cur_missions:
             mission_results.append(mission.attempt(equipment, self))
-            if not mission.available:
-                # Mission no longer available, so we clean up
-                self.missions.remove(mission)
         # Do the science
         self.points -= len(self.cur_allocation)
         if self.points < 0:

--- a/gamelib/missions.py	Mon May 07 00:27:59 2012 +0200
+++ b/gamelib/missions.py	Mon May 07 13:59:50 2012 +0200
@@ -38,7 +38,8 @@
     SHORT_DESCRIPTION = None
     LONG_DESCRIPTION = None
     MINIMUM_REPUTATION = None
-    available = True
+    # Flag for missions that can only be attempted once
+    completed = False
 
     def __init__(self, init_data=None):
         pass
@@ -47,10 +48,24 @@
         """Serialize the mission state for saving, etc."""
         return []
 
+    def can_attempt(self, state):
+        """Can we currently attempt the mission"""
+        if self.completed:
+            return False
+        if (self.MINIMUM_REPUTATION is not None and
+                self.MINIMUM_REPUTATION > state.reputation):
+            # Don't have the reputation completed
+            return False
+        return True
+
     def attempt(self, equipment, state):
         """Attempt the mission with the given equipment list.
         Returns a result object with the results of the mission."""
 
+        # Handle error case
+        if self.completed:
+            raise RuntimeError('Cannot attempt a completed mission')
+
         # No equipment is usually a special case.
         if not equipment:
             return self.attempt_no_equipment(state)
@@ -236,8 +251,6 @@
     MINIMUM_REPUTATION = 20
 
     def attempt(self, equipment, state):
-        if not self.available:
-            raise RuntimeError('Cannot attempt an unavailable mission')
-        self.available = False
+        self.completed = True
         return Result(SUCCESS, 0, 50, (
                 "Mount Rushmore is remarkably easy to destroy."))