According to Gamasutra, Limbo - which kicked off the Xbox Live Arcade Summer of Arcade last month - has sold over 300,000 units. The outlet spoke to Jeppe Carlsen, level designer for Limbo, who discussed some of the design philosophy behind the game. Carlsen noted that the team had a few goals that Limbo had to adhere to from the beginning, including the overall mood and the decision that it would contain no tutorial text whatsoever.

With many of the game's puzzles punishing a player at the slightest misstep, Carlsen stated that "it's important that you also treat him nicely." In other words, while death is frequent, it's also entertaining and educational. Ideally, players learn something about the puzzle with each death.

Another philosophy: Make sure the correct solution is "fairly easy to execute" and that incorrect solutions are obviously wrong. Making incorrect solutions obvious aids players in discarding them from other possible solutions, nudging them toward the correct one. After all, there's no better motivator than grisly death.