Minimalistic Gore Mod - Shooting someone with an SSG has a chance to blow a player's torso in half.
Ammo collection dropping - If someone has over double the default starting stock of an ammo type, they will drop some of it, helping to keep a richer ammo supply without overdoing it.
Team-based Pain Sounds & Taunts - Each team has their own taunt, and pain sounds.
Team-Colored Projectiles - To go hand-in-hand with the above, Rockets and Plasma are Team-Colored, so you'll know what you should avoid!.
Team-based Projectile Clipping - Your rockets and plasma do not explode when they hit a teammate! (They go through).
(Without sv_unblockplayers, which is bugged with this) This makes the more cramped maps much more playable with lots of players.
Team-based Player Clipping - You'll clip through teammates, but still bump into enemies.
4-Way Support - Play with up to four teams! Highly recommended.