Personally speaking, I'm probably going to personally consider this game as non-canonical instead of Divinity 2: Dragon Knight Saga.
I hate it when people just say "this", but this.
The first segment of the game in Fort Joy I was quite captivated by: the down-to-earth aspect of people in power being horribly but matter-of-fact evil was compelling and disturbing, and gave actors' stories some point and poignancy.
But once it moved beyond that, I dunno. The OS2 universe really seems to sit apart from the rest of Divinity, both in the style of its retelling and its lore. I've really struggled to make sense of it and I simply can't. DD, D2 and DOS made sense to me; BD I can't comment about since I never finished it, but nothing about any of them seemed difficult or incongruous. But unfortunately a lot of OS2 was both difficult
and incongruous. It's not what I would to consider to be the definitive Divinity: not only does it not work, it's kinda depressing.
I worry I'm being overly negative in saying that, but I really don't like the way it pans out.
