Reply To: Game Design
You can totally play DOOM with the mouse and WASD, just like you would any modern FPS (minus the fact that there is no vertical freelook). However, this requires manually setting the mouse sensitivity to a very high number (40+?) in the configuration file. The maximum setting available in the in-game Options menu would make the mouse too slow to be usable.
This is a great example of how the community figured out better ways to play than was envisioned by the original designers. DOOM was intended to be perfectly playable with keyboard only (and to be fair, it is perfectly playable with keyboard only). But once folks realized they can be much faster and more efficient playing with the mouse, the game changed. This opened the door to higher level deathmatching, and much harder, moster-packed levels, which are very difficult (some probably impossible) to beat for keyboard-only players.
