Happy Birthday!
I came across a multiplayer mod, NeoTokyo, for HL2 about half a year ago with a surprisingly awesome soundtrack. If you're into cyberpunk-ish electronic music, I bet you will like this.
I can't speak for the game itself, as there literally were no players online when I started it up. It's such a shame that this wonderful soundtrack is stuck to a dead multiplayer mod. This could easily have been in something like the upcoming Cyberpunk 2077. Seriously, it's that good.
The soundtrack has been released as a free download by its producer here:
https://edharrison.bandcamp.com/album/neotokyo-gsdf