Air

[Tavrobel]

It originated as a hentai game. Like WTF xD

So did Kanon; Clannad almost went the same way as well (fortunately, there's official Key Tomoyo porn in Wonderful Life/Tomoyo After). H-Game --> animes are totally all the rage right now.

I particularly liked it when (SPOILER)... all of it. GAO GAO STEGOSAURUS

EDIT: I didn't mean After Story. That's the one with (SPOILER)Ushio.