I bought dark souls 2, spent days getting murdered by skeletons near fire link shrine wtf, then spent days at the first fire place near the sniper on the bridge. I put it down and left it as soon as skyrim came out, though it was ok at best. Played skyrim until I got bored and a few months later came back to darkmsouls. Had no idea where I was, what I had to do.
I think I played like a year straight......it took like two play throughs before I had sort of a clue how to build a class lol.
Then I did every class type, every multiplayer clan, bought copies for my friends and bottomless boxed them through coop. Borrowed demon souls did a play through on that.
The combo of open world, class building, with non straight forward game integrated coop and pvp, plus great levels (ds1 and bb especially) can't be beat. Also I hate the fetch and quest dialog BS you see in most open world games, it really kills the suspension of disbelief. In the soul games you don't change scenes to have npc dialogue and the game is believable because it not not trying to be whole world but a slice of hell.
And yes it does ruin you for other games. I got a few weeks of play out of call of duty, I will play this new souls game for year at least.