Before mp_potential_step became bloated in later Studios, GM 8.1 had a clean motion planning system. The manual’s section on mp_grid is a masterpiece of technical writing. It walks you through:
This is the section most users are looking for when they search for the . It was (and is) an exhaustive list of every built-in function available in the engine. It was categorized logically, a structure that persists in GameMaker today: