I’ve open sourced this project! Minus the image assets, you are free to use, alter, etc. the engine under the MIT License. Check out the GitHub repository. I’m really interested to know your thoughts!

To see the engine in use, download the source and open it in Xcode, then modify MainScene.m with whatever you want in the main scene. As you can see, I’ve removed two image assets from the repository — the player sprite sheet and the tile map sprite sheet — so you’ll have to use your own.