Second point is, to launch, it would be nice to have big examples for incoming visitors to be attracted to the service.
Apropos the idea of multiplayer gaming, I have found that node.js and a smart bit of client-pool reflection has meant that I don't have to lean heavily on a 3rd-party API framework for the 'backend multiplayer' bit, because after all .. that's the good bit. Today's multiplayer game engine is a few well-spent afternoons with node.js, imho .. it does at least make just-in-time deployment very smooth. Don't forget that this is, also, a place for things like Lua and Rust to excel. I'm not trying to be contrarian, but these are the realms in which you dwell; a multiplayer API+(deployment problem solved with magic), versus having someone built such a thing in a month or 3, themselves, and consequently owning the codebase, because .. after all, the backend is where a lot of the magic happens when you've got 10's of k's of gamers online, and can watch it happen for months on end ..