Just tried it, the visuals aren't bad, but the player control and inventory management seem like an afterthought. The jumping physics feels especially unrealistic.
It does let you run it without downloading any "games" btw. If that's not the intended experience they shouldn't make that the shortest path UI experience.
but fwiw, I just tried mineclone and at least the jumping physics were better.
That's been a long running debate in the community, whether the "MineTestGame" should be included by default anymore. At some point MTG seemed slated to be even discontinued as a project, but instead it got some fixes for outstanding issues and kept intact.
In my case, when I was starting out, it was a nice way to incrementally add game features only when I was ready for them, with MTG being the base to start from. So I have a bit of a soft spot for it.