Cheats and Arcade Mode

Cheat Codes

After completing the game, all subsequent play will let you use the cheat codes that you've unlocked by finding intel pieces. To use a cheat, start a level, then hit the pause menu and select Options. The cheat menu will be available in that menu. You can't gain achievements while cheats are active.

Two Intel Pieces: COD Noir

Changes the game to black and white.

Four Intel Pieces: Photo-Negative

Reverts the game's colors so that black becomes white and white becomes black, and so on.

Six Intel Pieces: Super Contrast

Turns the contrast in the game way up. Can be combined with the first two effects.

Eight Intel Pieces: Ragtime Warfare

Protocol Chaplin Omega speeds up the game to 170% of the normal speed and adds an old-timey film filter and soundtrack to the game.

Ten Intel Pieces: Cluster Bombs

Every frag grenade you throw will explode normally, then detonate five more times after that.

Fifteen Intel Pieces: A Bad Year

Every enemy that dies will explode into a bunch of car tires. Very fun stuff.

Twenty Intel Pieces: Slow-Mo Ability

Pressing the melee button will toggle super slo-mo abilities, letting you pop heads with ease.

Thirty Intel Pieces: Infinite Ammo

Gives you infinite ammo while playing.

Arcade Mode

When you defeat the core campaign for the first time, you'll unlock the Arcade Mode. If you've played the Campaign scoring game in Halo 3, you should have an idea of what to expect here: you gain points for damaging enemies, killing them, killing them in unique ways (such as by stabbing them or blowing cars up while they're nearby), destroying vehicles, and so on. If you can move through a level quickly, you'll gain score multipliers if you manage to kill a number of enemies without taking any long breaks (20 seconds or so of no killing will reset your score multiplier). You can challenge your own high scores or try to beat your friends. It's a fun way to give the game some replayability, but keep in mind that you only have limited lives to work with. The harder the difficulty you play on, the larger your final score will be.