Press ENTER to display the chat console. Then, activate the following cheats by pressing ASTERISK and then the corresponding case-sensitive codes:

CHEAT FUNCTION - CHEAT CODE
Toggle no clipping - ghost
Unlimited health and ammo - cheat
Toggle AI - other
AI status - state
Suicide - suicide
Display frame rate - fps
Toggle maximum fps to 30 or 60 - maxfps
View credits - thunderdome
Display coordinates - coords
No clipping - ghost
Hit points locked - freeze
Programmer message - jzk
Programmer message - HoneyBunny
Next CD music track - cd_next
Previous CD music track - cd_prev
Stop CD music track - cd_stop
Play CD music track - cd_play
Increase sniper rifle zoom - WAR
Unknown - catco

Click the hidden button in the lower left corner of the main menu screen to enter a practice mode in any mission.

Press F8 during game play to enter Map mode.