This may be old news, but YoYo games is considering supporting the ability to export games built in Game Maker Studio for the raspberry pi. They have three games available for free on their site (http://yoyogames.com/pi).
At the moment, they’re gauging interest in this based on how many people download these games from their site. If Game Maker Studio could export games to run on a Pi, we’d see an explosion of content capable of being added into this platform.
One of the games (Super Crate Box) looks to be a pretty cool arcade platformer that I need more time with.
One of the games (Maldita Castilla) is what appears to be a well made ripoff of Ghosts & Goblins.
The 3rd game I haven’t tried because it needs a mouse.
Both of the games were super easy to get up and running on v3.6 of RetroPie. I’ll note here that these games DO NOT work on RetroPie versions prior to the Jessie build (v3.4?).
One unfortunate issue with these games is that there is no visible way to reconfigure the controls, so you’re stuck with z, x and arrow keys as the controls.
If you want to test these out on your retropie, it’s just a few steps. I’ll explain with the example of SuperCrateBox: