Similar to Dota/LoL/HoN but with Quake.
Runes such as double damage, invisibility, regen ect would spawn in the middle maybe every 5 minutes? Armor, weapons and ammo would increase as levels go up. Levels increase when u frag a player or frag bots/ which have modded health to balance the game.
Towers defend the base. 1st tower could be a frozzen bot with rocket launcher. 2nd Tower rail or plasma, Base buildings bfg and nades.

Cool, no?