anchor.diff:      ..spawnTime   = 1.8
       ..retreatTime = 0.2
       ..stayTime    = 2.8
  -    ..maxConcurrentNpc = 2
  +    ..maxConcurrentNpc = 3
       ..npcSpawnProb     = 0.02;
   
     LevelSpec lvl8 = new LevelSpec()
  
positive.code:     ..retreatTime = 0.2
      ..stayTime    = 2.6
      ..maxConcurrentNpc = 3
      ..npcSpawnProb     = 0.018;
  
    LevelSpec lvl9 = new LevelSpec()
      ..columns     = 3
  
negative.code:     ..retreatTime = 0.2
      ..stayTime    = 2.4
      ..maxConcurrentNpc = 3
      ..npcSpawnProb     = 0.04;
  
    LevelSpec lvl10 = new LevelSpec()
      ..columns     = 3
  