Alkemstone is a puzzle video game published by Level-10 (a division of Dakin 5) for the Apple II in 1981.

[1] The Alkemstone was hidden in the real world and the publisher offered a $5000 reward for the first person to decipher its location.

It was likely inspired by the popularity of the Masquerade armchair treasure hunt published in 1979 and still unsolved at the time of Alkemstone's release.

[2] The prize was never awarded and it is unknown if anyone solved the clues or recovered the Alkemstone from the location it was hidden.

[1] Johnson commented that "Don't buy this one unless you seriously intend to win the five thou and have a high tolerance for boredom.