I was around your age when I discovered the predecessor to TU, GMT (Garry's Mod Tower). I spent days upon days straight playing it
Also, I reccommend, when you're a bit older, getting figurines instead of pop figures. (They actually look like the characters, but are WAY more expensive. It's worth it though [from $40-as high as $200, sometimes even more] )
I might make another thread about it.