I started writing one in Gw-Basic for a programming project in high school. I quit half way through because everyone was doing the same thing. Instead I wrote a simple x&o program that go tbetter the more you played against it.
No, I don't claim to have created artificial intelligence but interestingly enough, I found the project for a game in a very old fashioned "Annual for Boys" kind of book. This book was already an antique but it had a section where you played a simplified X&O game and you filled a matchbook with colored buttons for each possible scenario. Each button represented a possible move for the scenario. If the game won, you put the button back. If it lost, you took the button out and played again. Super simple memory, long before the first computers were anything more than Tom Swift books.
Simple but impressive in many ways.
