Head to the difficulty files in your Crysis folder (for example: 
"C:\Program Files\Electronic Arts\Crytek\Crysis\Game\Config"). 
The four files you're looking for are titled "diff_easy.cfg", "diff_normal.cfg", 
"diff_hard.cfg" and "diff_bauer.cfg". Open the file (using Notepad) of the 
difficulty level you are currently playing 
or wish to edit. 
Add the following line to the end of the file and save it:

Result                                   Code 
------------------------------------------------------------
God Mode                               - g_godMode = 1
No Target                              - ai_IgnorePlayer = 1
No Weapon Limit                        - i_noweaponlimit = 1
Unlimited Ammo                         - i_unlimitedammo = 1
No energy loss                         - g_suitCloakEnergyDrainAdjuster = 0
No energy cost                         - g_suitRecoilEnergyCost = 0
Run faster                             - g_suitSpeedMult = 2.85
More armor points                      - g_suitArmorHealthValue = 900.0
Instant health regen                   - g_playerSuitArmorModeHealthRegenTime = 0
Instant health regen while moving      - g_playerSuitArmorModeHealthRegenTimeMoving = 0
Set health regen time to 0             - g_playerSuitHealthRegenTime = 0
Set regen time while walking to 0      - g_playerSuitHealthRegenTimeMoving = 0
No waiting until regen starts          - g_playerSuitHealthRegenDelay = 0
Instant energy                         - g_playerSuitEnergyRechargeTimeArmor = 0
Instant energy while moving            - g_playerSuitEnergyRechargeTimeArmorMoving = 0
Set energy regen time to 0             - g_playerSuitEnergyRechargeTime = 0
Do not wait until energy regen starts  - g_playerSuitEnergyRechargeDelay = 0
Extra health                           - g_playerHealthValue = 900.0
Set difficulty, "1" is easy            - g_difficultyLevel = 1
Speed suit never runs out of energy    - g_suitSpeedEnergyConsumption = 1
Toggle melee attacks while sprinting   - g_meleeWhileSprinting = <0 or 1>
Set swim speed; "4" is default         - pl_swimBaseSpeed = <number>
Walking movement speed; "1" is default - g_walkmultiplier = <number>
Toggle vehicle invincibility           - v_goliathmode = <0 or 1>
Multiplies punch strengt;"1"is default - cl_strengthscale = <number>
Koreans speak in Korean                - ai_UseAlternativeReadability = 0
Toggle frame rate display              - r_displayinfo = <0 or 1>
Spawn indicated item                   - i_giveitem <item name>


You can also modify your suit stats. For example:
-------------------------------------------------
g_playerHealthValue                        = 400.0 
g_playerSuitArmorModeHealthRegenTime       = 0 
g_playerSuitArmorModeHealthRegenTimeMoving = 0 
g_playerSuitEnergyRechargeDelay            = 0 
g_playerSuitEnergyRechargeTimeArmor        = 0 
g_playerSuitEnergyRechargeTimeArmorMoving  = 0 
g_playerSuitEnergyRechargeTime             = 0 
g_playerSuitHealthRegenDelay               = 0 
g_playerSuitHealthRegenTime                = 0 
g_playerSuitHealthRegenTimeMoving          = 0 
g_suitArmorHealthValue                     = 400.0 
g_suitCloakEnergyDrainAdjuster             = 0 
g_suitRecoilEnergyCost                     = 0 
g_suitSpeedEnergyConsumption               = 0 
g_suitSpeedMult                            = 2

After making all of your edits, save the file, load up a new game 
and see what you've edited!