The following are known Action Replay Codes for Apocalypse on Sony Playstation (PS1).

The codes should work with the region specified but may work for other regions as well.

Device Compatibility: Action Replay, CodeBreaker & GameShark

Infinite Lives
800FFEFC 0006

Have All Weapons
300FF9A0 0001

Open All Restart Points in the Level
800FF9C0 0001

Invincibility
800FF9A4 0001

Open a Debug Window During Game
800FF9C4 0001