Quake 3: Arena Cheats

Display the console at any point in the game (during game play or at any screen). Type /sv_cheats 1 then enter /devmap <map name>

Use the one of the following values for <map name>:
q3dm<1-18> or q3tourney<1-6>
Or, you can use any custom map (leave off the map extension *.bsp)

The game will load in single-player mode with the current settings of the bot variables, and cheat mode enabled.

Use one of the following item names with the /give code.

allammo
armor
battle suit
bfg10k
flight
gauntlet
grappling hook
grenade launcher
haste
health
invisibility
lightning gun
machinegun
medkit
personal teleporter
plasma gun
quad damage
railgun
regeneration
rocket launcher
shotgun
mega health
speed

In order to use cheat mode without being in single player mode, start a game, display the console window, and type /devmap <map name>, then press [Enter]. The level will start in cheat mode.