This is a typical tower defense game. Penguins with helmets on (and later on: in vehicles) start on one part of the screen and leave on another. The player can build towers (gun, flame thrower) and has to prevent the penguins from exiting. Money is earned by killing penguins. Enough kills unlock newer and better towers with other capabilities.
First level, penguins heading up the beach and leaving inland ("A day at the breach" [sic]) enhances the WW-II feel of this cartoonish action game.