Kingdom
One of the things that strikes me about Kingdom (on steam) is the restful way you play it it for the most part. The pixel art graphics slide their way across your screen pleasingly as you ride from one end of your kingdom to the other. Gawking aside the in game mechanic of spend coins, get stuff, spend coins, upgrade stuff, spend coins, hope that you get some return on coins, is nice and simple and stays just on the right side of scarcity to remain fun. Threat comes from the nightly wave of mobs, in this game I believe...