Is this an MMO game?
Nope. It's a pure single player game.
Have played for slightly more than an hour and done the first handful of quests. Works decent so far 4K with high details. Have noticed two issues though that were also mentioned in a German review I watched. Capes look awful, because they seem to have terrible physics. They just flail about wildly and behave in no way how they do in real life. That's just a minor thing though. What's worse is that on PC I have random frame drops (mostly) during cut scenes, but also while actually playing. So far, it hasn't really messed up anything for me, but according to the review I've watched it can also happen during fight scenes which would probably be more annoying than just having a slightly stuttery cut scene. Apparently, it's a known issue and there could be a patch for it on the actual release day. According to the German mag they were told they'd get a patch to improve performance for last weekend, but they didn't get it. There seems to have been a patch for today's early access start, but that seems to have changed very little. So, if you're on PC and don't have the game yet, you might want to wait a bit.