The Godot engine is a pretty good alternative for any of the 2D/3D open source engines out there. One if the features that got me excited about the engine was the Html5 support.
With one click of the button you can export the game onto any of the platforms android, iOS, mac, Linux and html5. The only problem... The h5 exporter didn't work right out of the box for 1.0 version of Godot.
I looked at it and was unable to figure out what was going on. I searched their forums, Facebook page and the only answer I got was that it was broken and that the devs knew about it.
The compilation was working fine but linking not so much. It would report a lot of unresolved symbols .. The basic things like gd script were not working. I had to look up how scons worked. Had to figure out why the existing build wasn't working. ... Then I came across a bug report that said that the emscripten was too strict about the order of object files included in an archive and would straight out not include them.
The solution for this was to use the default .bc format output for creating archive for emscripten compiler/linker.
I created a sample scons app to figure out how to change the build config variables and was able to get it to work. I quickly created a pull request for the build fix and posted it on Godot git repo.
I was able to learn scons and the emscripten both at the same time.
You can pick the godot build that works for H5 from here https://github.com/vkbsb/godot/tree/h5_canvas_polygon_fix