Of late, I've found
Unreal World quite addictive. For the most part, it's a gentle, non-violent, meditative sort of game, but it has a few little quirks here and there. Like the fact that, since the program treats humans like any other wildlife, the smartest thing to do after killing an enemy warrior (or discovering that your spiky pit trap was a little too good and has killed a hunter from the neighboring village) is to take all the dead man's stuff, butcher him, and preserve his flesh in your pantry in case of hunger.