PS2 Winback 2: Project Poseidon Cheats

Extra Characters in Multiplayer Mode:
Complete the game with A rankings in all missions on each game's difficulty. Any characters with "New" on it means its unlocked.

Extra Options:
Complete the game once. In the "Extra Options" mode, you can access all BGMs and Movies used in the game.

Shadow Stalker Difficulty:
Complete the game once. Start a "New Game" and select the hardest difficulty level "Shadow Stalker" will be unlocked.