Well it's for anyone! As long as they can read, lol.
13... Strange, I never thought to be the youngest so far...
I'm 13. I've been playing it since I was... eight? nine? I don't remember. I think anyone can play it. Young kids who can't read very well could even play it if a helpful parent or sibing was willing to help them. I think older people can enjoy the game too, if they look past the cutesy animal game surface of it.