Yume Nikki is a free game made by one man, Kikiyama over two years. I call it a game for want of a better word. There are no real enemies. You play through a girl's dreams and collect items. Once you finish, you drop them in the Nexus. Cut scene, end of game.
If you play it to experience it, though, you will find one of the most genuinely disturbing experiences in any media I've seen. The only time you'll feel comfortable with it is when it's setting you up to terrify you.
In the end, if you're looking at it as a video game, it fails. There is no story development, no threat of losing, other than getting transported to an inescapable room. Playing it as a psychological horror experience, it's one of the most effective things I've ever come across, and easily the best horror indy game I've ever seen.