In the add-ons screen, enter the following cheat codes:
Buffy the Vampire Slayer: Cheat Codes Free Download
Unlock arenas with multiple players:
Y, Y, White, Black, Black, Y, Y, Y, Y, Y, White, Black
Get unlimited health:
Y, White, Black, Black, White, Y, Black, Black, Black, Y, Y, Y
Get Killer Power:
Y, Y, Y, Black, Black, Black, Y, White, Black, Black, White, Y
Play as Dark Buffy in arena mode:
Black, White, Y, Y, Black, Black, White, Black, Black
Enter Arena Mode (Multiplayer Game):
YYW-BBY-YYY-YWB
Where: Y-Y button
W-white button
B-black button