Side note about “instant multiplayer Minecraft”: Minetest is as instant as possible for a native application: you download the client (about 25 MB), then connec

Side note about “instant multiplayer Minecraft”: Minetest is as instant as possible for a native application: you download the client (about 25 MB), then connect to any server, no matter which games and mods run there, and have all the needed assets streamed from it, too. Non-existing nickname is all the identification player needs, IRC-style. It is even inter-operable across major versions and forks, at least to some extent. Of course, it has been this way because it has a typical relatively small and tight open source community, but, from a cursory look, it is possible for a public server to have a protected spawn/sightseeing area with rules and information, then (auto)grant new players who want to participate various gameplay privileges based on their progress. It doesn't seem that web client built in the same manner is impossible. What's impossible is, most likely, telling a browser to give you a gigabyte or two of memory to keep the local world area, then step aside and forget about it.