Open  the console by pressing "~", then type any of the following
codes:

Code                                             Result 
REB GOD                                          God Mode 
REB INFINITE AMMO                                Unlimited Ammo 
NEXT LEVEL                                       Win Current Level and
                                                 Skip to Next
GIVE [character's name] [item name]              Give Item 
GIVE AND EQUIP [character's name] [item name]    Give & Equip Item 


Item List
     Example: GIVE GUNLOK LASER

Weapon & Ammo 

--- Laser Weapon:
LASER
BINARY_LASER
MAXIM_LASER 

Best Ammo: BATTERY_PLUS 

--- Plasma Weapon:
PLASMA_PISTOL
PLASMATRIX
PLASMAGNUM 

Best Ammo: AUTOLOCK_BOLTS 

--- Launcher Weapon:
GRENADE_LAUNCHER 

Best Ammo:
GRENADE_PLUS
GRENADE_EMP 

MISSILE LAUNCHER 

Best Ammo:
MISSILE_PLUS
MISSILE_EMP 

--- Flame Weapon:
FLAMETHROWER 

Best Ammo: NAPALM 

--- Special Weapon:
NANOFRAG 

--- Most Powerful Weapon:
EPULSAR 

Keys 

KEY
KEYB 

Shield 

SHIELD_PICKUP = Standard Shield
ARMOUOR_PICKUP = Heavy Shield 

Body Slot Upgrade Pickup 

AIM_ACCURACY_PICKUP
LOCK_DECODER
BEACON_TRACKER
TERRAIN_SCANNER
TERRAIN_SCANNER_WITH_RADAR
OMNI_SCANNER
HOLOGRAM_GENERATOR
AUDIO_CLOAK
SIGHT_PICKUP
SIGHTPLUS_PICKUP