Enter the following at the Options/Code menu, then activate them at the Options/Special
TRUBLVR All Levels FLSHWND Regenerator ANGMNGT Rage Meter to Max GRNCHTR Unlimited Continues HLTHDSE Double HP BRNGITN Double HP for Enemies MMMYHLP Halve HP for Enemies FSTOFRY Killer Punch BRCESTN Solve Puzzle NMBTHIH High Score Reset
Enter the following at any terminal in the game:
JANITOR Play as Gray Hulk SANFRAN Hulk Transformed movie art PITBULL Hulk vs. Hulk Dogs movie art FIFTEEN Desert Battle movie art NANOMED Hulk Movie F/X movie art
Thanks to Revolution readers Stealth and Peter!