Probably Elder Scrolls for me, mainly Oblivion, Skyrim, and Morrowind from most to least (though Morrowind I haven't touched in a while, admittedly). Mostly Oblivion, really, partly because I don't want to strain my low-end PC with Skyrim, partly because it's just so
relaxing, which is a very important part of any go-to game, in my opinion. I can just do the same silly quest(s) over and over and over again and not get bored. Sometimes I play it in-depth, really get into it, other times I just play an hour or so a week and then do something else.
Civ5BNW
What do you mean you guys don't play Civ anymore?
Sometimes I wonder wtf I'm doing on a Civ forum when, according to steam, the last time I played any Civ game was about half a year ago (but more realistically it's probably more than a year a few months, given that I recall when I tried playing again half a year ago my computer CTD's or BSOD'd and I took this as a heavenly sign that I shouldn't play Civ and just go back to TES).
I wish I had a go to game. I've found I've been losing interest in all my games lately. And there's no new games to interest me either. It means I spend my busy days wishing I was playing stuff, and my free days having no idea what to play. It sucks.
I go through periods sort of like that sometimes. But, generally, it fades away too and then I get renewed interest in whatever game(s) I get interested in.