This game left a very strong impression on me. It may be short, and it may be extremely simple in terms of game mechanics and content, but what little there is is so well crafted and gripping, I'm pretty sure I had chills running down my spine.  The daunting atmosphere and the psychological torment are just delightful, and I really commend the author for managing to condense the strengths that can be found in Sigh of the Abyss in such a smaller format. I feel like it's much easier to "wow" people with a big game rather than a small one (especially when production time scales with it), and Obsession achieved that for me.