Use the console brought up by ` you must be in Devmode or have entered con_restricted = 0 in the console previously. Any weapon item or attachment can be spawned using i_giveitem eg. i_giveitem SOCOM. You need to know all the different items names and they're a little criptic at times and case sensitive! Useful if you would like a specific item from the start of the game such as a sniper scope! You can also add some of the weapons from Multiplayer like mines and claymores to single player!

The codes can be entered in the console or in a user-created System.cfg file. The console must be unlocked by using "con_restricted = 0" before any of the cheats can be used in the console.

Locate the difficulty files in your Crysis installation folder (ie: C:\Program Files\Electronic Arts\Crytek\Crysis\Game\Config). These files are called diff_easy.cfg, diff_normal.cfg, diff_hard.cfg and diff_bauer.cfg. Open the file (with Notepad) that corresponds to the difficulty level you are playing. Add the following line to the end of the file and save it:

g_godMode = 1

Now, when playing your health will still decrease but you will not die. Instead, your health and armor will automatically replenish when your health reaches 0.

Additional Cheats
Using the same method as above, add the following lines to the end of your config file for the corresponding effect:

Code: Result:
i_unlimitedammo = 1 Unlimited Ammo
ai_IgnorePlayer = 1 Enemies Ignore You
i_noweaponlimit = 1 Carry Unlimited Number of Weapons

NOTE: ALWAYS MAKE A BACKUP BEFORE OVERWRITING GAME FILES.