Press ~ during game play to display the console window, then type sv_cheats 1 to enable cheat mode. Then, enter one of the following codes at the console window to activate the corresponding cheat function.

Effect	Code
Brain target practice	impulse 102
High jumps	sv_gravity 2
Invincibility	buddha
More weapons	impulse 101
No clipping mode	noclip
Spawn katana	give weapon_katana
Spawn stunstick	give weapon_stunstick