I was around 30 already when the Descent 1 demo appeared, and for me this game was a revelation. I had played Doom before, but it wasn't my cup of tea really. Descent however had me the moment the entrance room of Lunar Outpost appeared in front of me on my monitor, moving slightly up and down as my ship gently wiggled.
Descent's gameplay is very unique because of the full freedom of movement in all three spatial axes. For its day (and if looking at what many game devs consider "AI") the robots (the game's "NPCs") had a very good and quite diverse AI. Depending on your point of view, gameplay of the first two titles of the series can seem bland or refreshingly straight forward, which is very much owed to the abstract and artificial nature of the levels and lack of unique and varying tasks and goals in different levels. Still the basic principle of the game seems very appealing to me.
On the other side, if you are looking for great and frantic multiplayer action, Descent imo still is one of the best games out there. It greatly rewards skill, offers a huge variety of explosive gadgetry and allows for creative gameplay.
There are also several fan-driven mod projects improving the game and allowing to run it on modern OS's and hardware. If you really want to enjoy Descent even today, you should download and install one of these.
The one I prefer (and maintain) is D2X-XL, which allows to play Descent and Descent 2 in vanilla mode like in the old days, but also has a ton of optional enhancements for those who like to try a fresher flavor of Descent, offering high resolution textures, better models, improved sound, colored light, many effects (smoke, fire, lightning, weather, glow, etc. - stuff that is standard today), and much, much more, and on top of that has Oculus Rift support.
There also are great new missions available for D2X-XL, breathing new life into Descent with diverse, detailled levels, improved graphics, new level mechanics and non-standard objectives.
D2X-XL runs on MS Windows, Linux and OS X. Find it on http://www.descent2.de