CowBobs is a freeware game that is made by the developer of the OHR RPG Game Creation engine. There's not much of a story behind this game. You are Bob the Hamster (mascotte of Hamster Republic). The main thing is to shoot as much cowboys as possible. But they will also shoot you of course, so it's you or them.
You have to use the mouse to kill these enemies, which might work very bad in DOSbox, but it'll work fine in Windows.