i want my purge and poison towers to attack things that still have their abilities or aren't poisoned. its no use otherwise because they do too little damage
game is too samey: Just a few stats to upgrade, most games of this type give you a wider variety of upgrades, like repair centres, additional weapons like missiles, shields, outlier turrets etc. All inbound vehicles move same speed, move directly in, and just move close and fire. Adding some variety - say attacking units that can launch temporary shields, long range missiles, fast vehicles that spiral round etc would improve gameplay.
Also I dont like the button that caused me to leave the game. Couldnt work out waht had happened until I read the other comments. Lost the game had to restart.
On the positive side, graphics, turret movement, game balance (attacker vs defender) all good - so a solid base to build a more interesting game on.
the messagin system needs to be toned down a bit. i send perfectly normal sentences, such as: 'i had a muffin for breakfast'. and it takes away half the word!