All codes work only in the game for one player:

RAMBO - all weapons, 30000 ammo and all keys
TANK - 200% health and 200% armor
FORMULA1 - run like crazy (the word FORMULA is written together with the number 1)
IDDQD - die immediately
BULLFROG - you will jump very high
GOODBYE - complete the current level

CBVCBV - opens all doors / presses all buttons
UJHTW - immortality
GJITKYF - go to level XX; possible values XX - 01, 02 ... 18, 19
,TKSQJHTK - the ability to fly using the jump key (only in versions 1.35 and 1.40)