',' and '.' could also be used to strafe with a single key press, but this seems like a bit of an afterthought and was not mentioned in the manual. Advanced engine needed : Vanilla compatible Primary purpose : Single player Title : Big Fucking Speech 9000 Filename : bfs9000.wad Release date : April 28th, 2017 Author : 1337 Doomer Email Address : redacted Other Files By Author : 64.wad, brutalst.
In the case of doom specifically, the arrow keys were used for moving/turning, control was used for firing, alt was used as a strafe-modifier and space was used as the activate button. Weapon selection was on the number keys, which was easy to remember, but not so convenient to press. Other important controls were typically in locations intended to be convenient for the left hand, often on modifier keys (presumably to minimize the possibility of key rollover issues).
The default control setup in many FPS games of that era (at least, Wolf3D, Doom, Duke3D, and Quake), revolved around using the right hand on the arrow keys for moving forwards/backwards and for turning. In FPS games of that era, players were not expected to (and in the case of doom, could not) explicitly aim vertically, they just had to aim horizontally and the game would take care of the vertical component.