ESDF is Dynamix's little take on the regular FPS movement configuration of WASD, implemented by Dynamix in Tribes 2. Look at your keyboard. The keys in WASD and ESDF are in the same place in relation to each other, so all you have to do is train yourself to place your left hand a little to the right and it's all the same. But why do it at all? Look at your keyboard again. When you use WASD you have the surrounding keys at your disposal for actions and inventory management and whatnot, except to the left where you have keys like Shift, Caps Lock, and Tab that you may not want to or cannot bind to whatever actions you desire. But switch to ESDF and now you have the same number of keys, plus Q A and Z! Nifty? Maybe not, but in a game like Tribes 2 with many weapons and items and commands and communications it all makes a difference.