It was the mid-1990s, and 3d was taking off. While Doom and Wolfenstein 3d pioneered the first-person shooter genre, and games like Starfox were getting things off the ground on consoles with simple on-rails space combat, games were ready to take things to a new level of freedom.
Six degrees of freedom, specifically.
In Descent, you explore mines looking for trapped miners, destroying virus-infected mining bots, and destroying the reactor core and escaping before the whole thing comes crashing down around you. You do this by moving in true three dimensions, allowing your ship to not only strafe in each direction, but turn and spin as well. It was a truly transformative, and in some cases, dizzying experience, though even as someone that easily gets motion sickness, I was never really affected by this game. The game had very worthy sequels as well as a spin-off series (FreeSpace, which wasn’t really related except by name with its first game) that moves the series to open space, and was very good as well.
The game’s source has been released under a restricted license, allowing for non-commercial source ports to be created. I use the “dxx-rebirth” engine under GNU to play the game, and it plays very well without having to fiddle with DOSbox.