some food for thought:
section one doesnt meat the medieval/historical category, but i think has some merits for your review
Vampire survivors.. ok its not "pretty" but its addictive as a time filler. + Co-op coming
unrailed - if you plan to play with him ?
The Book of Unwritten Tales - pretty
Creeper World 4
Golf With Your Friends - single or alone
Lego Games - co-op
Oxygen Not Included - looks ok might be to complicated / building and management
Portal - might be to fast to play in some parts but over all its a puzzel story game
Forts may be to quick to play so maybe : ShellShock Live / Worms -
Subnautica - its pretty + story + base building
Besiege - build stuff
Mindustry - build stuff with a small threat
Unheard - Voices of Crime
Murdered: Soul Suspect - detective
The Witness - walking
The Wolf Among Us - point andclick / story
World of Goo - its Goo!!!! its world of Goo!!! every one should have this!
plants vs zombies - old but classic good addictive fun
section to meets i feel the medieval/historical category
Myst
Timberborn
Dorfromantik
Euro Truck Simulator 2 - driving around a to b being a buisness man.
How can you say no when the theme is :
edit remove already mentioned ones