Jet Set Willy is a platform video game written by Matthew Smith for the ZX Spectrum home computer.

Players navigate Willy through 60 screens of the mansion and grounds, collecting glowing items while avoiding hazards and guardians.

Jet Set Willy included a copy protection measure in the form of a card with coloured codes, making it more difficult to duplicate.

Various expanded versions and ports were released, as well as third-party editing tools that allowed players to design their own rooms and sprites.

Willy's mansion was bought with the wealth obtained from his adventures in Manic Miner, but much of it remains unexplored and it appears to be full of strange creatures, possibly a result of the previous (missing) owner's experiments.

Willy must explore the enormous mansion and its grounds (including a beach and a yacht) to fully tidy up the house so he can get some much-needed sleep.

He is returned to the point at which he entered the room, which may lead to a game-ending situation where Willy repeatedly falls from a height or unavoidably collides with a guardian, losing all lives in succession.

This was caused by an error in the path of an arrow in The Attic, resulting in the sprite traveling past the end of the Spectrum's video memory and overwriting crucial game data.

[10] Reviewing Jet Set Willy for Your Spectrum magazine in June 1984, Sue Denham wrote that the game was "every bit as good and refreshing as the original".

[15] A version of Jet Set Willy for the Commodore 64 was released by Software Projects and ported by Shahid Kamal Ahmad.

[16] The original releases of Jet Set Willy for the BBC Micro and the Commodore 64 also contained bugs which made it impossible to complete the game.

The Software Projects version that was sold in the UK is dated 1984 and was programmed by Cameron Else, co-winner of the Jet Set Willy competition.

[18] It received generally poor reviews which criticised inferior graphics and animation, but Rob Hubbard's theme music, unique to this version, was considered a highlight.