To activate the cheats in Xonotic you might need to change the hotkey for the ingame-console.

Under "settings" select "input". There you will find under "client" the entry "enter console".
This is usually set to ~ (tilde) and should be under ESC on an US-American Keyboard.

To activate the cheats you need to start an server yourself, it doesn't work as client.

The command "give" cannot be disabled, while the command "sv_cheats" can be activated with "1" or deactivated with "0".
All other commands can be toggled, so every time you type them in you either enable or disable them.


Activate Cheat Mode:
sv_cheats "1"

Deactivate Cheat Mode:
sv_cheats "0"

Attention: The cheats only become active after the next map has been loaded.
You can also restart the server to load a new map.

God Mode:
god

No Target:
notarget

Go Through Walls:
noclip

Fly around:
fly

Get all Weapons, 999 Life, 999 Armor and from every ammo type 999 units:
give all