Playable on the phone:
Globally launched a couple of days ago - a voxel-based sandbox game designed purely for Facebook Messenger. Of course it’s a clone, BUT with extremely simplified building process, vertical screen orientation, working UCC and distinct progression system. Oh, and it’s 3,93 MB! (initial download size)
If you encounter any bugs or low FPSes on high-end phone, let me know!
Things provided by Playcanvas we were super happy with:
- Open-source engine, read its code alot while trying to understand some non-conventional technical problems
- Collaborative editor and cool branches management
- Lightweight builds - as that was the main requirement and the main choice criterium
Things that were pain in the ass 
- The fonts system - doesn’t work well with logographic languages. (because of the download size we minimized some languages to the characters used in the game; so right now Chinese players cannot see their names in the rankings)
- Encountered a couple of bugs we had to fix with some hacks overriding the engine functions. Sometimes we didn’t exactly know what we were doing :).
- With a game consisting of 20+ window types, the lack of prefabs system was a little inconvenient. We placed and disabled everything on the main scene. But, FYI, even though the scene json is huuuuuge, it loads and works well.
I hope Playcanvas will be developed further and get more popular among the developers. Good luck!