The abbreviation should tell you everything you need to know.
This is a platformer engine that I made because I wanted jump-through / one-way slopes in my game. The fact that this works in any capacity is an affront to God, but it gets the job done. It includes:
The code is commented in a way that I like to call "I considered commenting a hobby". I never want to touch this again, and so A. I only commented what was absolutely required for me to understand what was happening at any given time, and B. The chances of my providing any form of support, moral or otherwise, for this project are almost 0%.
Feel free to contact Liam Jacobs (that's me) on the Game Maker Forums if you are really struggling. I can't say that I will be able to help you, but I will try my best.
A few notes:
End User Licence Agreement (EULA).