Editor’s note: This essay was originally published in 2019. I have made minor edits in this republishing. There was a MathOverflow thread about mathematically interesting games for 5–6 year olds. A lot of the discussion revolved around how young age 5 really is, and how we should temper expectations because we don’t really remember what it’s like to be 5. In response to an enormous answer by Alexander Chervov, user LSpice quipped, “‘Daddy, daddy, let’s play another in the infinite indexed family of perfect-information draw-free cheap-to-construct two-player games!