Last time i tried Luanti (when it was still called Minetest) I ran into serious bugs rightaway. I reported them and a year later they still weren't fixed. I hope the quality has improved since then. It's nice to have a free alternative for programming classes etc.

Minetest sort of officially rebranded itself as a game engine when it changed name, it already was a game engine before that. Most of the bugs are caused by games and/or mods themselves, in particular if you had a Lua exception.

Among the various games that took inspiration from Minecraft (Voxelibre, Mineclonia, Repixture), some are more reliable than others. Those that don't try to be too close are the more reliable because replicating complexity tends to lead to more bugs.