Steam

Exactly. Kids these days.

For clarification if you dont get it:

You had four keys for motion: wasd

Two for rotation: q and e.

You couldn't necessarily change your perspective independent of your plane of movement. This had to be done simultaneously.

Strafing as its currently understood didnt exist until your 'perspective' became un-fixed from your ability to move. It was at this point that the shooters became 'truly' 3d.