I have a lot of fun playing the board game Quarto! 
I challenged myself to make in a few days a virtual version of this game where you play against an AI. The algorithm is rather simple, but still challenging. It is based on a variation of the minimax algorithm that I made before even reading anything about zero-sum game theory... I discovered later that it exists some advanced researches about the implementation an AI for this game. You can find it in this paper.  

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