i dont see why its much of a good game
Because
you're an idiot with stuff taste it does everything right. The weapons feel good. Its difficulty is reasonable.
The level design (for the most part) is great. No hand-holding here. You figure out where to go, and if you feel like you can do it better, you do it again. You keep doing and you find different ways of completing a level. You're not thrown down the singular path that the developers have designated the "correct" way.
Also, its playerbase continues to create maps as well as gameplay mods/source ports
to this day. The game's almost 20 years old, I'd say that's pretty damn good in terms of longevity.
Bonus, the majority of the music is made up of Slayer/Pantera/Metallica/Alice in Chains covers.