I've enjoyed a great many hours in RimWorld. It has charming visuals much like Prison Architect, but you're building a colony with a choice of different AI behind the scenes.
The game has sold over 120,000 copies directly from its website (myself included, I personally purchased my copy long ago). The developer has also given me a Steam key recently.
The Steam release marks a huge new "update 14" which includes a new scenario system, the amount of possibilities with this system are huge. It also features Steam Cloud saves, Steam Workshop support, new animals, new things to build, improved AI and it's just a huge release!
Note: It's Early Access, so it is not finished!
RimWorld is one game I can recommend without hesitation. Very few games get such an easy mark from me, so do check it out.