The following passwords start you at various points in the game. You get a password every 4 levels. Note that "0" is zero.

• THE OLD WAREHOUSE (after the green slime level):
  J723P0 T2WL5J GFY2FV
• ASTRALNET CHEMICAL PLANT:
  N723PB 0V49WJ GBGYP4
• THE OUTSIDE ZONE:
  S72AG0 3R40Y9 48YX7Y
• TUNNELS (this last password starts you 3 stages before the last stage):
  XT2AG0 3B4AYR 48A97S