Many people have complained about the difficulty stating that its only a matter of minutes before they get swarmed by the A.I.

I'm working on a way to make the difficulty curve more gradual (e.g. rounds and waves that get tougher as you progress),
and I'm in the process of drastically improving the navigation system of the enemy A.I.

Basically, while you have the same number of enemies in the field, only a certain number of them are allowed to navigate towards you.
Others enemies will spread out in the field moving towards turrets (if any) and decoy beacons; even if the enemy is only 300 pixels away from you.

They're is of course so much more to do:
[*] Cash System
[*] More enemy units (including tanks)
[*] Vs. mode
[*] More weapons
[*] More special abilities
[*] Comprehensive interactive tutorials
[*] Better graphics and sound...

So please stay tuned...