There are only a few games that truly calm me down to a level that is healing mind and body, and those games are HoMM, Dungeons 2 and ESO.
In that list, ESO is definitely on top. The music, the atmosphere, the incredible quests (for an MMO standard, that is!)... Yeah, I fucking love ESO. Maybe that's also because I was never one of the deluded nutjobs that thought ESO would be Skyrim, but online.