While the first game shared the title of "Descent," it had nothing to do with Descent. FreeSpace was a flight sim, while Descent was a first-person shooter.
FreeSpace 2 is the only one I've played. For a game that came out in 1999, the effects are quite epic, with capital ships wailing on each other with beam cannons.
Some levels have you flying through nebulae (annoying, very), making it hard to see and pretty much punching your FPS in the face. Well, my FPS at least.
I'm pretty sure this is abandonware.
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Here's a small .gif from Wikipedia. Not very easy to see, but it gets the point across.
