Technically it's fine, however unless there's a really good gameplay reason, I'd recommend also include strafing and moving backwards (and following the other recommendations on the jam page) - it's what most people will expect, and they'll generally enjoy your game more if the controls don't get in the way. That being said, there can be good game design that restricts this in various ways - Peacemaker in a previous year which had no keyboard controls at all, which greatly added to the stress as you were fumbling with the mouse to reload your gun while at the same time trying to run away from approaching horrors.