Thankfully there is Minetest, an open source alternative that’s been around since 2010. Clearly it doesn’t have the same social pull that Minecraft has, but there is a nice little community that maintains MT and last time I checked there was an easy to add mod that attempts parity with all of Minecraft’s features.
Discussion
I did also dig into this cave once. However, I don't remember finding a mod for minetest which added features to hold my grip longer than a few hours into minetest. Can you please provide mod name or better an URL?
Sure enough, librekitty said it. It’s all been renamed and polished since I last looked in. Minetest is now Luanti, and the in game browser is where you can find the MC parity development called VoxeLibre.