2001
Microsoft A.I. Puzzler was a game being developed by Alexey Pajitnov of Tetris fame, and who previously worked on Microsoft Entertainment Pack: The Puzzle Collection. It's official website has at least two snapshots on the Wayback Machine dating from July 28th 2001 to August 1st 2001, with its first inaccessability date being August 9th 2001, which meant that the game was shelved between the August 1st and 9th timeframe. It also used to be mentioned on Wikipedia's List of video games published by Microsoft page with the earliest dated from June 15th 2011 and the latest prior to removal being being October 12th 2020. All that remains is just a scan of the manual.
