I wanted to be a bit more productive in my spare time, but I have made a huge mistake:
I started playing Vagrus - The Riven Realms again.

The world building in Vagrus is excellent. It's set in a post-apocalyptic fantasy Roman empire, and there is a massive amount of text that details the world, and the people living in it. There is so much to read, that the devs even thought it necessary (and rightfully so) to display a warning about the sheer amount of text on the game's startup screen, with the suggestion to refund it if one doesn't enjoy a lot of reading. Sooo, of course this is the perfect game for me - or would be if I had more spare time.

The game is a mixture of trading sim and role playing game. You play a vagrus (a caravan leader), and travel the land trading wares, transporting passengers, spreading gossip and doing missions for different factions, you also have a lot of story elements that you can (and should) follow. There is turn-based combat, and during story events there are plenty of skill checks.

The game is relatively difficult, due to its interwoven mechanics. You need to calculate relatively tightly in order to make a profit, but if you loose people in combat, not having reserves might lead into a morale-loss and hunger death spiral... Also, due to the game's grim settings, the choices one faces are more often than not to either do what is right, or to survive.