You have one goal in this game -- and that is to DESTROY ALL! In this game, though, you have to manage money well so you can buy equipment to attack and protect yourself from other exterminators. How do you do that? You start off with a pistol and each time you win a level, you can go back to the menu page and use the $$ earned to buy. Heck, you can go to battle with no weapon (Dunno if that would be wise though). Buuttt...if you get exterminated, you lose $$, dun dun dun, so if I were you, I buy when I get the chance.

WASD or arrow keys to move
Spacebar to pick up weapons
Left mouse click to Shoot