The unit counter is a bit slow. You can exploit this to get 9 units. When you have 7 units and enough mana for 2 units click two times very fast on the unit you want and you will get two of them giving you a a total of 9 units
There is a bug, where sometimes in the room with the hole to the next level, when you walk into the bottom part you can't see enemies and items anymore. The game continues however and if you defeat a enemy in the bottom part where you can't see him, you get unlimited xp as long as you don't move. You alsog get unlimited items, although you have to pick them up blind. If you walk back up you sight returns and you can see them lie. Use it for unlimited POWER!
This game is terrible. Too much camping, spawnkilling and way too powerfull guns make this almost unplayable for low level players. Plus the leveling and money getting is waaaaaaaaaay to slow.