The thing itself: http://yal.cc/r/gml/ Blog post: http://yal.cc/introducing-gmlive/ In short, through a lot of trouble I made a GML->JS compiler that works closely enough to the original one. Then it is hooked up with a special project build and runs very similarly to how actual GML code would on HTML5 target. Also there's a matching code editor. And other things. As result, you can write and execute GML code right in the browser, in real-time (Ctrl+Enter to run). This can be used for a lot of things: Feedback is welcome.