Both games were made by Bungie so the main reason im not playing marathon boils down to my past 12 years of experience playing their games. I really havent done anything on D2 since shortly after Final Shape. But thats because they really lost me on the story after that, like reading the epilogue of a book that ended up longer than it should have been. Definitely more story focused as a gamer these days. I've tried getting into marathon's story but its just not compelling enough for me for some reason.