Simple and not complicated, maybe add another level of difficulty that would require a bit more skill other than holding down the left mouse button once every monster wave comes.
There's a graphical glitch as well in the hard level pack, either way it takes you into ninja kid castle. It would be better if you actually allowed for some difference in play style and a little glitching capabilities but with the engine you're using and the fact that you have yet to administer the remedy to the "Wind walking" i.e. walking on thin air glitch, then I suppose I'm done for the time being until the next update.
Muny, You do understand that in agreement to the COPPA and KONG ToA you are breaking them both? You're suppose to be 13 to register an account (i'm not reporting because I would be breaking a rule, but please be more careful next time)
Great game, The strategy behind it is completely Crowd Control, Upgrade your main turret for flag ships, and use your miniturrets as defences against other ships.