become a millionaire games

What is the children’s book (for about 5th/6th grade) about a young boy who becomes a millionaire?

He is sick and codes a video game, which ends up getting him a check in the mail for a million dollars/pounds. He goes out and buys a bunch of stuff, like a Rolls Royce, but eventually just spends it on a mansion because he likes the pinball machine in the front hall. I remember this from about 6/7 years ago, when I was in 5th/6th grade.
[No, Enano, not Millions]

MILLIONS

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