A
Star Trek game written by
Eric P. Allman (the same man who wrote
sendmail,
syslog, etc.) in May of
1976.
As Captain of the Enterprise (or if you screw up during the course of the game, the Faire Queene) you attempt to eliminate a certain number of Klingon ships wreaking havoc throughout the Federation.
The source is worth perusing if you're learning C being that the program's rather small and incomplex. The game's worth playing if it's 3AM on a Saturday and you're especially bored. Look for it in /usr/games/.