I've been looking at the map attached below for a while, but I'm quite confused...
I'm no programmer, and the person who have done the map is quite obvisouly one...

Can anyone here explain the principles behind the smooth baneline movements?
Just treat me as stupid as you want.
TY very much

~Unholy

What in particular? He decreases speed in the direction last moved in over time if buttons aren't pressed, nothing magical. I use something similar in Mech Combat, only implement it differently. Just have speed decrease over time. <_<.

everything.. D: ... but w/e i'll try to focus my question

You're working with unit movement speed. When the user presses a button of WASD, the baneling's speed is set to x and it moves in that direction. When no buttons are pressed, a periodic function decreases movement speed until it hits 0. This might be using a more advanced system where it takes into account previous velocity (for example, you maintain your previous X-axis speed even if you're only pressing a Y-axis button) but all that takes is some simple math to recalculate where you're ordering the unit to go.