Lumi was bored. She had played games, read her books, and watched anime, but she didn't have interest in any of that at the moment. Maybe she should code something? Perhaps a little game to amuse herself. Tic-tac-toe would be simple enough... but impossible to win against a well coded AI.
What if she made the board three dimensional? Then in a cube with a side of three the first player would always win... unless you increased the side to four... and while she was at it... why not make the game board four dimensional? Projecting a four dimensional hypercube into two dimensions would be aesthetically more pleasing.
She set to work. The game board would be visualized as five by five squares, each a slice of the hypercube, arranged as a larger five by five square. Enforcing the rules of the game required some mathematical tinkering, to ensure all the possible victory conditions would be checked. The AI began placing random marks, only blocking the human player when necessary, but soon grew more cunning, aiming for victory from the beginning.
It was well past midnight, when the game was ready. Lumi set two AIs to play against each other, marveling her creation, the game board filling with marks at incredible speed. Sometimes one of the AIs would win, sometimes the game would en in a draw, new one beginning soon after. Then she set out for a game against her own creation...