Version 1: Hold down the 'Help' key and keep it pressed while pressing 'Fire' and you'll get infinite lives and can move through the levels by pressing the numeric keys '1' to '0' and the minus key.

Version 2: If you have the latest version, then attempting the above will reveal the message: "Congratulations!, you have found the cheat mode... unfortunately it has been ZZAPPED!". If this happens, go to the control selection and type "scrap 28" and then start the game. The effect is the same as above.