Mojang did some charity game jams from 2012 to 2016 in which mojang developers made several small games in a limited time period. These included Catacomb Snatch, Nuclear Pizza War, Endless Nuclear Kittens, Battle Frogs, Nuke the Dinosaurs, Docktor, Snake Oil Stanley, Healthcore Evolved, Shipment 23, Blackout, Bureaucrap and Manor Road. However, most of these games don't seem to actually be online anywhere anymore and were only given away for a very limited time period on the humble bundle site.
More info here: https://minecraft.wiki/w/Mojam