How about freeminer?http://freeminer.org/ . Freeminer is a opensource fork of minetest. It is availble for Mac, windows, linux, android, freebsd, and openinidaina in binary or source packages. The game is also compatable with both minetest and freeminer servers. also you can't install the deb on ubuntu 14.04 with out both the main .deb and the freeminer data deb, there is also a server deb file you should install. Please not you can't install freeminer and minetest at the same time as you will wander into a dependacy issue with minetest-data. This does not effect the mac/windows verson. also if you are running android for your main desktop please note most voxal open world games on the google play store are pirated illegal forks of minetest that violate the GPL so it is best to stay away from them. also how about voxelands http://voxelands.com/ and terasology http://blog.movingblocks.net/blockmania/, voxelands is another game like minetest and I think it is a fork of minetest, but don't quote me on it, and is an opensource voxal game for mac, windows and linux. Terasolaogy is another minecreaft like game and when people see it they often think it is just a texture mod at first. Both are good games to be on this list. And of chorse there is minetest its self http://minetest.net/, minetest is updated regulerly and it is worth installing their ppa to get the latest verison of minetest. As you know minetest has a decent amount of mods for how big it is and unlike minecraft all the mods mostly work as long as you got the minium version the mod needs, like for example a mods needs build .82 and you got .98 the mod will still work, unlike in minecraft , just be aware that lots of mods are depentant on other mods so you will offten have to go through the arcives in the mod forum to fide the old mods, for example lots of mods need the fire or wool mods and those are in the arcived mods section, so you should get to know the forum, also minetest now has an online mod repo, just know it does not work correctly as of yet. Minetest is available for OSX, widnows, linux, freebsd, solaris, andorid (unofficle, and officle as whell as illegal forks), openindiana, PC-BSD, and there is an OUYA port as whell.