Since the codes are out I will just do a layman explaination. After pudge cast the hook, the program pause pudge activates the render function. During the render pudge hook will check for distance and for hook target else it travels forth, if there is someone hooked or when the distance is reach it travels in reverse and the other checks for when the hook returns. Once it's done the caster is return to normal it's very simple.
Edit; Thus, pudge wars was made to complicate things and add more entertainment to the already overpower (if it lands) ability on itself.