After playing this game for a while, I'd say that it's one of the good ones out there. It's recommended if you're into survival and adventure genre. It offers not-so-complicated, yet not-so-simple ways to make things. Unfortunately, it's lacking natural method of creating. Capacity of some tools are infinite, such as candle. It's probably based on the minetest_game. I guess that it contains a set of extending features, though i must admit that it's better to have a set of minimal features. The complete specification of the game wasn't published.
At the time of this writting, the performance's good when it's running on a medium computer (say, 4GB RAM and CPU 1.5 GHz). Crash of the minetest engine has never occured, though the software didn't reponse for a while.
Texture's the best one (compared to others), though i don't like cube graphics. (the animation is weird because of the machine, as most games' are. It's a little disapointed).
In-game documentation is sound and good, but i advise you to explore in the game for yourself. You should know some information of minetest in the minetest wiki. (when you know something, it isn't interesting any more :))
For now, number of mods are increasing. Wonders if you can make game for minetest engine without mods? There're many limitations of the minetest engine. Despite the limitations and flaws in the design, you can play with this engine and game.