Open Source HTML5 Puzzle Game Engine
Try it out at https://www.puzzlescript.net.
If you're interested in recompiling/modifing/hacking the engine, there is development setup info here. If you're just interested in learning how to use the engine/make games in it, the documentation is here.
This fork is primarily meant for use in my PuzzleScript projects. Feel free to use it yourself, but for now it'll be tailored to my needs and I may make breaking changes.
See https://github.com/OnatronGD/PuzzleScript/wiki for a list of features I've added and plan to add.