I like the Ren'Py project, a popular game engine aimed at Visual Novels - that can also be used as a portable Python environment.

One limitation was that it required downloading games, while nowadays people are used to Flash- or HTML5- based games that play in-browser without having to (de)install.

Can this fixed? While maintaining compatibility with Ren'Py's several DSLs? And without rewriting everything in JavaScript?
Can Emscripten help? While this is a Python/Cython project?
After lots of experimenting, and full-stack patching/contributing, it turns out the answer is yes!

Live demo:
The Question Tutorial Your game

At last I finished organizing and cleaning-up, published under a permissive free software / open source license, like Python and Ren'Py themselves.
Python port:
Build system:

Development in going on, consider supporting the project!