Regarding the 6-hours talk: Sonic is not about playing each levels once, if you do that, the game is short, yes. However, there are 5 red rings hidden in each level, several alternative paths, shortcuts and so on. Also, besides the red rings there are also time attacks, which are not easy. I have played the game for 40:28, which is playing through the game, collecting all red rings, getting most S-ranks (I still need to get three more, so I'm not done yet). Also, there is some small extra most will probably not do, but I'm shure I will end up north of 50 hours because of this. Without counting replays just for fun that will definitely also happen. Mind you, I'm a Sonic fan, so if you just want to run through the game once as quickly as possible, you will possibly end up disappointed by the length.