Silkworm

Silkworm is a classic horizontally-scrolling shoot-em-up. The main difference between this game and many other side-scrolling shoot-em-ups is that you will be on land as well as in the air. The first player would play as a helicopter, but if a second player joins the game, they would play as a jeep. Both players would have to protect each other as well as themselves. (mobygames.com)