Here's one that's been a long time coming
Unreal Tournament.
I used to play UT99 and UT2004 so incredibly much when I was younger that the OST has burned itself into my brain. To anyone, I would just recommend putting on the entire OST (especially of UT99*) and listening, but for the sake of this post, here's some personal highlights as percieved by yours truly:
UT99:
The Course (Michiel van den Bos)
Botmca#10 (Michiel van den Bos)
Superfist (Alexander Brandon)
And my two favorites:
Foregone Destruction (Michiel van den Bos)
Go Down (Alexander Brandon)
That's just a small list, of course, there's a lot of other great songs in the series. Somewhere, you just have to make a pick.
As for UT2004, as the game's OST is a whole lot larger and more homogenous to a degree, here's a small sampling of the game's many worthwhile tracks.
KR-Corrugation-Rise (Kevin Riepl)
KR-Roughinery (Kevin Riepl)
level13 (Starsky Partridge)
level16 (Starsky Partridge)
*It's not that UT99's soundtrack is necessarily better than that of UT2004 unless you are into synths more, but it's generally more varied, making for a better listening experience overall.