TYhis is really good but it seems that levelling up on strength does nothing. . . the enemies turrets seem 400 times more powerful than mine and if I attack a nest with 20 bugs in it and a turret guarding, with my nest of 300 bugs and 3 turrets, there is still a stalemate and the enemy is able to sustain. Tip for everyone: SPEED NOT STRENGTH!
This is the same case as most tower defense games on here. . . it starts off fine but as you go along you simply do not get enough money to buy/upgrade the towers, and eventually you are swamped by too many enemies.