Can someone please EXPLAIN THIS?

[lavagamer_agar.io]

how he did that?

 

[BloodSoul]

Well, that map has nothing that blocks a unit's path at all, so it's easy to deceive the others. The author simply used SetUnitX() and SetUnitY() combined with "A unit is issued an order targeting a point" event. Then, store targeted point and periodically move it until it's close to that point.

Also, PurgeAndFire has made a system that modifies/breaks that limit. However, it says that you should avoid using high numbers.

 

[PurgeandFire]

Movespeed has a hard limit of 522. But you can simulate higher movement speeds with a system like this:
MoveSpeedX for GUI v1.1.0.0

But it definitely gets buggy the higher you set the movement speed. Units will sometimes skip over their target location, and group movement becomes finicky.