To activate a number of cheats, pause the game by pressing the 'Space Bar' and type "THE REAPER" (with or without the space). This will automatically activate the infinite lives cheat and give you the ability to select your favorite weapon by using the keys 'F1' to 'F7'. To recharge your weapons, press the 'F10' key. To skip levels, pause the game and press the 'L' key.