The stories barely overlap. If you watched a full let's play of the first Darksiders you should be good, you can even just read the wikipedia article and that should be enough.
I have a few problems with Darksiders 2, but overall is a good game. Halfway throw the game, it almost felt like the developers ran out of time (or money maybe), because it feels very rush; that's probably my biggest problem with the game.
Nintendo and PC gamer








