3rd level of this:
So this is technically not actual collision layers . . . it’s a solid object collisions system that I made completely from scratch.
Basically this allows the player or enemy objects to be non-solid to each other (they can pass through each other) but still collide with the ground and not pass through it.
The system itself runs on the Proximity and Position behaviors and nothing else, and is pixel-precise in how it calculates collisions (you never clip into or through a wall). This is done by literally checking every pixel step of the movement in order, which has positives and negatives to it (the biggest negative being the performance dips when travelling at high velocities).
Other limitations include that the ground objects cannot move at all and that so far the player objects have to be squares (though if the Proximity behavior had other shape options or if the Collision behavior had a “check” input this could be modified to work with them).
By the way, the AI here is extremely primitive (it’s just set to move random directions every second)