While playing, type in the following:

www.freespace2.com

You should get a "Cheats Activated" message. Then while pressing and holding 
the tilde "~" key, enter any of the following codes:


Code:	Effect:
0	Scroll forward through all primary weapons. 
9	Scroll forward through all secondary weapons. 
Alt+G	Mark all bonus goals complete. 
Alt+Shift+K	10% damage to your target.
Alt+K	10% damage to yourself. 
C	Send message to enemies. 
I	Invulnerability. 
K	Kill target. 
G	Mark all primary goals complete. 
O	Toggle Descent-style physics. 
R	Issue a rearm request for target. 
Shift+0	Scroll backward through all primary weapons. 
Shift+9	Scroll backward through all secondary weapons. 
Shift+C	Toggle availability of countermeasures for all ships. 
Shift+G	Mark all secondary goals complete. 
Shift+I	Toggle invulnerability for target. 
Shift+K	Destroy targeted subsystem. 
Shift+W	Infinite Weapons for ALL ships, including yours. 
W	Infinite weapons for just YOUR ship. 

PLEASE NOTE: You can’t advance in the campaign if you use these cheat codes. 
With one exception:

Go into a single mission scenario and use the infinite weapons cheat. Now exit 
the scenario (you don’t have to complete it) and return to the campaign. 
You’ll now have an infinite number of missiles, but will be able to advance in 
the campaign normally.