Although it might seem kind of silly now, a lot of people used to play first-person shooters with the keyboard. Mice have been a popular computer accessory since the mid 1980's, usually bundled with paint programs or operating systems. Still, when it came to games, people just continued to push buttons, just like they did on their SNES or Sega Genesis. Using a mouse seemed like an awkward way to play anything but a strategy game.

There was a game put out by Electronic Arts in the early 1990's called Magic Carpet. You were a sorcerer who flew around the world on a magic carpet killing evil monsters and such with your magical powers. It was a fully-textured 3D game, not unlike Descent in that matter, but what was clever was the controls. You steered the carpet using the number pad or arrow keys, and you aimed and shot at things with the mouse. It took a while to get the hang of it, but once you did, those creepy monsters didn't stand a chance.

Maybe I just played this game too much, but whatever the case, I was hooked on the mouse+keyboard combo. This was, of course, completely impractical in Doom since the whole idea of Mouse Look hadn't been built into it yet. When Quake came out, though, things got really interesting.

I may not be the best Quake player, but out of all the people I played with at the time Quake came out, which was a bunch in an ISP's tech support department, I was the only one who used the mouse. I was an average player against all those keyboarders, save for a single level, called The Ziggurat, which was a "low gravity" one where when you jumped, you would fly around for a long time.

Since most of the players were somewhere in mid-air at any given moment, aiming at them with the keyboard was virtually impossible. Mousers completely ruled that level, and the keyboarders hated it with a passion. I would be there blowing up endless keyboarders, one hand on the mouse look button (backslash) and the other on the mouse where I had configured the middle button as run. At the time, I don't even think there was an option for locking mouse look on.

By the time Quake II came out, I think most people had realized the superiority of the mouser and had adapted. Mouse look became a standard feature, probably only turned off by people who still prefer rotary dial telephones.