Work in progress: Flatris has been recently redesigned from the ground up and turned into a multiplayer game with both UI and server components. This has been an interesting journey and I plan to document the architecture in depth. Stay tuned.
Contribution disclaimer: Flatris is a web game with an opinionated feature set and architectural design. It doesn't have a roadmap. While I'm generally open to ideas, I would advise against submitting unannounced PRs with new or modified functionality. That said, bug reports and fixes are most appreciated.
Thanks @paulgergely for the initial flat design!
Also see elm-flatris.