[Delk]

AFAIK a similar thing worked in in lots of shooters: running diagonally by strafing and going forward gave you sqrt(x^2 + y^2) speed probably because of a design oversight (and because running in each direction was equally fast). In Descent you just added up/down for another axis, which gave you a speed of about 1.7x compared to forward only.

In Descent 2 and 3 you also had the "afterburner" which gave a speed boost forward, but it had limited (albeit quickly recharging) energy, and the speed boost it gave you was greatest at 100% energy and effectiveness dropped as remaining energy dropped towards 0%. So people learned to pulsate it multiple times per second so that it would recharge between the fraction-of-a-second uses and keep at ~95% all the time instead of quickly dropping to low figures.

So if you wanted to go really fast you'd both run diagonally in three dimensions and keep pulsating the afterburner multiple times per second.