Love(the engine behind mari0) was ported to the web a couple days ago. And they tested it with this http://tannerrogalsky.com/mari0/
Yes that's right Mari0 running in your browser. It can also run on your pi if you have one. But there is a couple issues with it if y'all have not noticed. The shaders were originally made for 0.8.0 and opengl. Web browsers use opengles. So that means that shaders will have to be tweaked. Also currently there is no networking in the love web port so sadly you cant make a multiplayer mod work in the browser yet.
If you want to help fix the shaders than the repo is here. https://github.com/radgeRayden/future-mari0
It runs on 0.10.0. If you find any bugs report it to the issue tracker and if you can attempt to fix it.