Fusion is an action game in which your job is to find nine pieces of a fusion bomb scattered over 13 levels. There are two craft at your disposal: a fighter and a detachable ground vehicle. To find the bomb pieces, many enemies and their spawning points must be destroyed. Barriers block the access to other levels and keys must be found to open them. Certain areas can only be reached by the ground craft which is not as powerful as the fighter, however - some careful planning is required.