Serious Sam Cheat Codes for XBox

Cheat mode:
At the main menu, hold the Left Analog-stick and press Black, White, Y.

Mental mode:
Successfully complete the game in Serious mode, then start a new game. Mental will be fading in and out under Serious. In Mental mode, all the enemies will appear and disappear.

Binary counter:
In the Great Pyramid stage, just before you enter the pyramid, you may have noticed a panel above the entry with alternating I's and O's. This is a timer counting down in binary. The timer starts at 1,023 and goes down from there.