While playing the game type "www.freespace2.com". A message will show "Cheats activated". Then the following combinations of keys will change the state of a cheat:
Press "~" and type:
|[Shift] + K||Destroy Targeted Subsystem|
|W||Unlimited Weapons - YOUR SHIP|
|[Shift] + W||Unlimited Weapons - ALL SHIPS|
|G||All Primary Goals Complete|
|[Shift] + G||All Secondary Goals Complete|
|[Alt] + G||All Bonus Goals Complete|
NOTE: You CANNOT advance the mission if you activated the cheat codes. These codes may only work under Win95/98.
You go into one of the single missions and activate the unlimited weapon cheat. Leave the single mission (you don't have to finish) and return to the campaign. You will now have unlimited missiles and keep the ability to advance in the campaign.