Devmode / 3rd person-view :

Make a crysis.exe shortcut from either the 32 or 64bin folder (or use that one exsists currently e.g on your desktop),
then right-click, properties and in the shortcut tab.
Look in the target line and after the location of your exe file type space and then "-devmode"  without (") and click Ok.
You should now be able to use F1 third person view in single and multiplayer.

Weapons and items :
   
If you want to cheat some Weapons or other items you have to run Crysis into "Devmode" (s. above) or either you
you must start the "restrict"-mode by typing in "con_restricted 0" without (")

Here are the commands for some cheats:

AVMine - Anti Vehicle Mine
AssaultScope - Assault scope
C4 - C4 with detonator (automaticlly)
Claymore - Claymore
FlashbangGrenade - Flashbang
GaussRifle - Gauss Rifle
FragGrenade - Grenade
GrenadeLauncher - grenadelauncher
FY71 - Korean Rifle
LAMRifle - Laser Aiming Modus for Rifles
Hurricane - Minigun
SOCOM - pistol
DSG1 - precision sniper rifle
LAW - rocket Launcher
Shotgun - shotgun
SmokeGrenade - smoke grenade
SniperScope - sniper scope
SCAR - standard US Rifle
SMG - submachine Gun
TACGun - sac Gun

others :

i_unlimitedammo = 1 - unlimited ammo for your character
ai_IgnorePlayer = 1 - the KI will ignore you and won't try to defeat themselves / the KI ignores you complete
i_noweaponlimit = 1 - will kill the weaponlimit, so you can take more than 2 Weapons with you
g_godMode = 1 - will activate "God" -Mode / woundlessnes will be activated

Load custom map :

To load a costum map you must go into "restrict" -mode [by typing in "con_restricted 0" without (")]
and then you have to type in the command "map" then a space and the mapname ...

=> 1. Type in : "con_restricted 0" (without " ")
   2. Type in : "map mapname" (without " ")
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by Goldsteal