First one I was familiar with to have it then
I think it's due to the transition phase games went through to being true 3D, that I considered FPS games having it as grown up and matured, if that makes any sense. Quake in a way, was a wakeup call to the possibilities for the genre's future. When you think back on these games, it's amazing things we take for granted were originally innovations, like mouselook in Quake
Oh man, how did we do without it?
Haha, I played lots of DN3D back in the day. Those were fun times. There's a group remaking it that officially got the go-ahead from Gearbox after being impressed with what they could do, though I haven't heard anything much. It might have been delayed. If interested, look up DN3D Reloaded. The same team is rebooting Rise of the Triads.