Oisac

Oisac is an action game where the player moves a crosshair over single screen levels and has to shoot down enemies, who are soldiers of an empire called Oisac. The enemies, which come in different abstract shapes, appear in the middle of the screen and will start moving towards the edges. It's necessary to shoot them down before they do so because if they leave the screen some of the player's shield will be depleted. When the shield, which is not rechargeable, is completely destroyed the game ends. To complete a level twenty enemies have to be shot down. In addition to regular enemies there are also ghost ships which are extra important to shoot since if they leave the screen all of the remaining shield will be destroyed.