On the brag screen, try typing in any of the following: "ASSASSIN", "SUPERFROG", "PROJECT X", "ALIEN BREED", "THE ONE AND ONLY", "PSIONIC CREW", "BODY BLOWS" or "PSIONIC SYSTEMS".

Enter "MIDAN" on the high score screen. The game replies with "You are a Fat Little Git". This cheat allows you after losing all lives, to restart the game on whichever level you died on, instead of level one.

On the first mission (The Landing), climb up to the highest possible point of the left-hand side of the first tree you come to until you are blocked by the leaves and type "NICEVIEWFROMUPHEREMATE" (it's also been given as "ACEVIEWFROMUPHEREMATE"). The border should flash and unpause the game (it will have paused from the "P" in UP.) Infinite energy will now be yours and the in-game keys will be activated.