I'll always have a soft spot for Minecraft and it's open world base building goodness.

If you want "Minecraft, but more grown up," I can't recommend Vintage Story enough. It's actually an offshoot of a survival modpack for Minecraft if I recall correctly. A more involved crafting system (i.e. knapping tool heads out of stone, casting and forging metal tools, etc) and a threatening winter make for a very fun survival game. Still in active development with a pretty good pace of new content regularly, and a lively mod scene.