They’re the closest things you’ll get to actual cheat codes these days. They have various effects - such as vampire mode, where health doesn’t regenerate and you gain health by doing damage, to larger explosions, to Big Head mode.
So what is there to unlock in Gears of War 3? Read on and find out. Nowadays though, especially with the advent of achievements, things are more tightly regulated. Sad? Sure, cheat codes were fun back in their day. You won’t be putting in code sequences in a text box, or mashing button combinations before certain logos appear at startup, but there’s still plenty to access. Console players have to deal with the built-in modifiers and unlocks, and activate them in just the single pre-planned way.
PC players may be able to play with the console, but that’s a whole other issue. Unfortunately for all you amoral scoundrels out there, what we typically think of for cheat codes simply do not exist for console versions of the game.