Hands down, the best games from the 90s was Descent. The first 3D, 360° shooter. This game forced me to buy one of those fancy joysticks that would allow me to really become one with my environment. When Descent 3 came about in 1999, my computer of the time was barely able to play it. I purchased the Linux build of Descent 3 which was my first Linux game I purchased and I still enjoy it today from time to time as it is still a blast to play.
Descent 1 and 2 have been open sourced and you are able to get updated and upgraded graphics which only make the Descent experience that much better.
For more info:
OR for those running openSUSE
Truly, a great game!