Assassin is a "shutem'up" arcade game set in the distant future. You are trained pilot who is fighting inside enemy territory. At the beginning of every mission, you get orders by your superior, and then you can choose among four different vehicles. Each has its own advantages and weaknesses. Destroying enemies gives you bonus weapons, ammunition or restores your shields. At the end of every mission you have to destroy big-bad-boss, powerful and dangerous enemy ship.