2. He left a huge void in the world of FPS gaming. The "best" FPS games today (Battlefield 3, Call of Duty) are graphically beautiful, watered down, crap for console gamers. Their actual game play sucks.
Quake1 Netquake Deathmatch/CTF/Clan Arena/Rocket Arena is still more intense and more a test of skill than any other game to follow in the ~13 years since it was created.
Creating a modern replacement (for no other reason really than fixing a few minor issues and bringing in new players) is on my list of Things To Do.