[Boudica]

Personally I'll say RimWorld. Its sorta like the sims. You've crash landed on an alien planet and have to manage colonist. Gather food, make weapons, defend yourself, that kind of stuff.
The objective is pretty simple, its to make a spaceship and get the hell out of there. It'll be a long journey though and you'll start to get attached to your colonist and watch many of them die and go insane, they might be kidnapped or you might accidentally harvest their organs. Yeap, you're in control. You decide everything.
Its one of my favorites and its a lot of fun.

For such an adorable looking game, it's surprisingly brutal. Oni has played it a few times and it looks good.

I personally play Conan Exiles a lot. Survival game with mmorpg elements. You can build anywhere, fight everything on the map, even kidnap people to become slaves, but there's also a story line and loads of dungeons. It's experienced it's fair share of bugs and growing pains (the authorities at funcom took it out of EA way too early), but I have a lot of fun on it. We also have our own server!

Here's some of the stuff I've built below:

Eastern Town including an inn


4x4 Researcher's Base