Among the print and play games there are gems for solo play that should not be omitted.
Micro Rome by Michael Bevilacqua, and it's expansion Aegyptus is such a game.
The game is fairly simple. It contains 17 two sided cards. The player draws a card, selects which of the two available sides to use, and places it over previously placed cards following simple rules (at least 3 fields of the earlier placed cards need to be covered, buildings need to be covered completely, etc.)
And that is it. Simple but effective and highly addictive.
Micro Rome can be played as light pastime in 15 minutes, or as a serious brain burner, in which case it will take more time to decide the best placement of the drawn card.
Anyway, no solo gamer should be without a copy of this game in the collection. Files for this game are free on BGG, so go get them.