Update: Here is a combined version of all three parts: Three puzzles on mathematics computations and games. Thanks for the remarks and corrections. More corrections and comments welcome.
I have a very strict December 20 deadline (self-imposed, I missed the official one) for my ICM2018 paper. I plan to talk about three puzzles on mathematics, computation and games, and here is a draft of the first third. Corrections and comments are very welcome! This part is around the simplex algorithm for linear programming.