A true classic -- not just one of the earliest games but arguably also the earliest game adapting an existing IP, albeit of course without permission. From the days when nerds were nerds, and only nerds would both play around with computers and like Star Trek.
There were different versions of this for many platforms; I fondly remember the C64 (or *a* C64 version, I guess, there were probably others) which had nice some nice sprite-based graphics for the Enterprise, Klingon ships and your photon torpedoes and phasers as they moved across the screen.
Obviously primitive by modern standards, even in gameplay terms, but well worth preserving as a piece of gaming history, especially the way the different versions built on top of each other. Almost everyone who was around in that time probably played *some* version of this game for their hardware.