Hope this helps
I agree with coffee about yondemasu.
Slice of Life
I really don't think C fits here well. Sure it has a "game", but the series itself isn't like a sports game, the game is more comparable to the God Game in Mirai Nikki. It's more of a mystery or a drama. As in it's more similar to Mawaru Penguindrum or Steins;Gate, not a traditional mystery.
The Supernatural, Blade, Deadman Wonderland are the closest series to the Horror genre. Supernatural is pretty gruesome, but they aren't your typical Elfen Lied or Shiki that you would associate with the genre usually.