Well… that is certainly a new one to me. You're an alien, and you're abducting and mutilating cattle, while avoiding… other aliens? You also get a cow's plaintive thoughts between missions, and you find them underground, and on top of steel girders. It's pretty strange. Arrow keys to move, hold Shift to use your abduction ray. From the game's documentation, this is a port of a game that was released in December 1989 as a doujin software for PC8801 in the comic market.