Xerix is a scrolling shooter for DOS. In this game, aliens have arrived and are bombarding Earth with a toxic level of radiation that will wipe out the human race with enough time. In response, Earth makes a reply by sending an advanced fighter to deal with the deadly mothership.
In Xerix, the fighter is destroyed with 1 hit. There are a wide range of enemies and obstacles on the way to the mothership core, so the unlimited number of lives is necessary.