Just a couple comments on Limbo -- I bought it, I enjoyed it, I played through it several times and will again. However, I still think the price of $15 is too high. I'm sorry.
Now first, allow me to defuse the "you pay that much to see a movie in the theater that's only two hours" crowd with NO I DON'T. I do not go the the theater more than once or twice a year BECAUSE of that price that you are arguing people are willing to pay. For most movies, I am not. I will wait for them to come out on Netflix and watch them at home. There are very few movies that are worth that cost to me BECAUSE of the entertainment versus cost ratio.
The thing that Limbo was closest to in my mind was really more like a board game, almost a Chutes and Ladders type thing -- going up, going down, going up, going down. That made me think that a lot of those puzzle units could have been interchangeable or random. I think an interesting add might have been to have a pool of puzzle segments that could be linked together in different orders for later playthroughs. On one occasion you slide down the hill and have to jump over a bear trap and the next you find a button that launches the buzzsaw -- something to keep you on your toes.
As it is, at least half the people who play this game will only play it once, because other than picking up the achievements or stopping to admire the monochrome roses, there is no replay value. In that sense, you are paying $5/hr of fun. That ratio is too high for my cheapassness. Maybe not for some, but it is for me. $10 would have been more in the park and $7.50 would have been probably about right for me. As it is, I actually plan on letting a friend and my brother both play the game over here so that the $15 is more easily spread out across three persons' experience, which makes me wonder how akin that is to them "stealing" or "duping" the game, since a one-time playthrough experience is what most of us bought, and what I would be sharing.