For multiplayer, do you have to unlock it while doing the missions in single player or should it be already unlocked ready to go? This is just fustrating me. elusivereaches - 8 years ago
Top Voted Answer
You need at least two controllers plugged in for it to be 'unlocked'. Swirlz - 8 years ago
Some of the arenas will be unlocked as you progress through the single player game. However, some of the levels will not be open for 3 or 4 players without a cheat cartridge.
This is intentional due to mild glitches that occur in them with more players. It was simpler for Rare to simply lock those levels for more players than to correct the glitches. Gunbladelad - 8 years ago