I finished the single player campaign in about 10 to 11 hours today. I'm heading out of town for an extended weekend, tomorrow, and wanted to get play through it before I left... I'm beat... I was definitely stumped a couple of times, but it was basically a lot more of the same this time around. Even a few of the puzzles felt completely ripped from the first. Not that I really minded. I had a great time playing it, and next week when I'm back in town and near my Xbox I'll have a go at the coop story. I see a lot of people are complaining about this taking 5 to 8 hours to complete. Maybe if you're using a guide, but I was moving at a pretty good clip throughout. 10 to 12 seems more realistic for someone who isn't just trying to run through it. Now that it is all said and done, I also appreciated that this time was balanced equally between running/exploring and testing. It definitely didn't feel like two half games like the first did. Anyway, now to sleep...