Thirteen isn't an unlucky number for this Limbo walkthrough; it's the number of videos in this series, a series which shows you the complete process, through trial and error, life and death, and as least amount of edits as possible.
Limbo is a minimalist game, specifically a 2D side-scroller puzzle-platform video game, with film noir aesthetics and an eerie atmosphere. It's available for download from the Xbox Live Arcade (XBLA). If you want to beat it, then this walkthrough series is how you're going to do it. If you ever need help, just resort back to here.
Mahalo describes the gameplay as… "…players take control of a young boy who traverses through strange and extremely dangerous trap filled environments in search of his sister. The game features a unique black and white art style with blurry backgrounds to emphasize the eerie atmosphere of the game's world. Animations are extremely fluid and objects and creatures react naturally to the laws physics, leading to some disturbingly graphic deaths that befall the young protagonist."