I'd personally say the word "genius" in this context is getting used as an adjective, which It's not - the adjective form is "ingenious". "Boy genius" is idiomatically preferable, as indicated elsewhere. Stack Exchange community consists of 183 Q&A communities which include Stack Overflow, the largest, most trusted online community https://thegeniuscrowwalkthroughp70466.bloguerosa.com/35419166/how-to-get-all-levels-in-the-genius-crow-secrets