The perfect balance of bullet-spongy enough that who shoots first isn't guaranteed to win yet not too bullet-spongy that you can't get multi-kills. The perfect balance of not spawning so close to people that you immediately die when you spawn yet you have that quake movement capability to get to the action fast. The perfect balance of greatly rewarding your skill but allowing you to be useful to your team if you aren't the best player. Various servers with their own configurations so you get it how you prefer it. Glorious headshot sounds. Even Splash Damage themselves haven't been able to top their own gem yet. Do yourself a favor though by looking at ETLegacy instead. It is an actively developed fork that is still improving the game after all these years, and is compatible with the original.