In the singleplayer campaign, cheats are ussualy enabled by pressing the ~ button to open the console. The cheat codes are:
bighugmug it gives the player all the weapons and maximum ammunition.
vivalahelvig makes the player invincible to gun fire and falling off from high cliffs. (except high-preasure steams)
heehoo gives the ability to fly around but when the player gets in contact with any liquid the cheat goes off.
camera1 it changes the player's FOV camera to first-person mode.
camera2 moving the FOV camera around away from the respective player.
camera3 third-person view camera mode.
Red Faction II
Enter the following code at the "Cheats" sub-menu, which is found at the main screen by going to "Extras", then "Cheats":
This will unlock all in-game cheats. It has to be "activated" by putting a checkmark next to it. You can also access this menu during game play by pressing [Esc], then going to "Cheats". The cheat options are as follows:
Restore Health - XXYWYWZ All Weapons - Y Unlimited Ammo - YWXZYZXW Unlimited Grenades - ZXZYXZXZ Select Level - ZYXWYZXX Finish Game - YXYX Rapid Rail Mode - ZYZYXXWW Gibbed Explosion Mode - WZXYWZXY Gibbed Ammo Mode - XXXXYZXX Extra Chunky Mode - ZZZZWXZZ Directors Cut Mode - YXZWZXYW Walking Dead Mode - XXXXXXXX Wacky Deaths Mode - WWWWWWWW Rain Of Fire Mode - YYYYYYYY Bouncing Bombs Mode - ZZZZZZZZ Explosive Mode - X