Cheats:

 Type these codes in, whenever you need them:

 [Ctrl][Alt][I]  -  Invulnerability
 [Ctrl][Alt][L]  -  Extra live
 [Ctrl][Alt][F]  -  All weapons
 [Ctrl][Alt][N]  -  Warp to the next level

 From Ren‚ Thiel, Gl”the