Hareraiser is a computer game, originally released in 1984 in the UK for most home computer platforms. It was released in two parts; Prelude and Finale. The game takes the form of a series of graphical screens depicting grass, sky and trees with occasional text 'clues'. There are no hints as to how the puzzle can be solved but presumably, the position of the trees, sun, clouds etc
A prize worth £30,000 was on offer if the game could be solved. It was released in two parts; Prelude and Finale. The solvers of Prelude would also then have to buy and solve Finale. They could then enter a competition to locate the prize, the bejewelled 18 carat "Golden Hare" pendant as featured on the cover. Hareraiser was never solved, and the hare was sold at a Sotheby's auction by the creditors in 1988.
Source: Wikipedia, "Hareraiser", available under the CC-BY-SA License.