I personally don't think there is an age "restriction" on Minecraft. I mean, I've met people who are 15-16 who play Roblox, and that's for sure a more childish game than Minecraft. Also, what is childish about Minecraft? What about it, makes it childish? No one has ever really brought up a valid reason as to why this game is meant for children. I mean, 95% of people will look at the graphics of a video game and say it's childish just because it doesn't look good. It's like looking at Mario and saying it childish, but that's not the case. If Minecraft had realistic graphics (which you can make it look realistic with shaders and a resource pack) then people wouldn't say it's childish, and I can almost guarantee that. You could also say the same about Roblox, however Roblox really was specifically designed for younger audiences so it truly is a childish game. However the map maker on it is kind of neat.