Chronium B.S.U. is a free and open source top-scrolling arcade space shooter game. You control a fleet of robotic fighters that you use to destroy your enemy. The objective is to protect the cargo ship (Chronium B.S.U.) at all cost, you can use weapons or crash your ships into your enemy.
Mac OS X 10.4 or newer
Intel or PowerPC powered Mac
Free download at noquarterarcade.com