Invasion From Beyond Cheats
PS1 | Submitted byGet all upgrades, ships and weapons
When you see the PRESS START screen, press L1, R1, L2, R2, Up, Down, Right, Left, Left, Right, Down, Up.
PS1 | Submitted byLevel select
When you see the PRESS START screen, press L1, R1, L2, R2, Triangle, X, Circle, Square, Square, Circle, X, Triangle. Go back to the Start Mission screen and you can pick all the game levels