All Characters: Zeiram Zone
Playstation
At the menu screen quickly press Right, Down, Down-Right, Down, Down-Left, Left, Triangle. You should hear a "whack" sound and the Game Start" letters should turn red. Start a game or a versus match. A new menu should appear that allows you to play as any character. Note: The enemies have the same HP as in the game. Pick a bunny and you're easy pickings. Pick Zeiram and your near invulnerable.
Extra Mode:
At the menu screen hold left for several seconds, then quickly press Right, Circle, Triangle. You should hear a "whack" sound and the option letters should turn red. You can now enter options and select "Extra" mode where you and the enemies are energized and sped up!
Versus Mode:
At the main menu, rotate the joystick 360 degrees then press X, Square, Circle, Triangle. If done correctly you will hear a sound and Versus Mode will be available.
Thanks to Revolution reader Jason Sommerfeld!

Embark on an inspiring mission of human connection beyond the UCA. Sam — with companions by his side — sets out on a new journey to save humanity from extinction. Join them as they traverse a world beset by otherworldly enemies, obstacles and a haunting question: should we have connected?