No official cheat codes were released for Psi-Ops. The game (2004, Midway) uses Unreal Engine 2 but exposes no console by default.
PsiOps.ini (usually My Documents\PsiOps\System\ or install folder).[Engine.Engine]: ConsoleKey=Tilde (or Tab).God, Fly, Ghost, AllAmmo.Most UE2 games disabled console in shipping builds. May not work.
SaveGame.sav before any trainer/CE use.PS3 version (Psi-Ops: The Mindgate Conspiracy on PSN) runs well on RPCS3. Has built-in cheat menu (L2+R3) in some custom firmware PKGs. More stable than PC port.
Enjoy the psychic powers — they're the real cheat code.