I'd say 10+ though a gifted 8 year old might love it too.
It looks like an incredible piece of software though! Lol I'm 33 and just downloaded it. If you had a more mature tileset in your presentation video I think you could easily target an older demographic.
I did notice some swearing one one of the games, since kids are going to download this this could be a bit of an issue. Perhaps a maturity rating and parental code in the future?