animations were there for the taking ..." Caswell cites Rogue as his inspiration for the randomised room layouts, and the electronic game Simon as his inspiration for the musical checkerboard puzzles. The hovering balls were inspired by the Rover "security guard" from the Prisoner TV series. The Commodore 64 version features early use of digitized speech: "Another visitor. Stay a while... stay forever!" and "Destroy him, my robots!" The digitized speech was provided by the company Electronic Speech Systems, who drastically raised their prices after Impossible Mission became a successful test case. Epyx did not deal with ESS again as a result. Caswell recounted: The game's title was one of the last elements to be finished. According to Caswell, "The choice of a name was delayed as long as possible, and Impossible Mission was more resorted to than chosen. It was, at least, somewhat descriptive, and the obvious allusion to Mission: Impossible was expedient, to the extent that both the game and the TV show involved high-tech intrigue." Reception In March 1985, Computer & Video Games rated the Commodore 64 version 38 out of 40 and awarded it Game of the Month. In May 1985, Zzap!64 editors ranked Impossible Mission second in their list of the best Commodore 64 games, while readers ranked it first, with 26% of votes. Citing Impossible Mission as example, Compute!'s Gazette in 1986 praised Caswell as "one of those rare people who has all the skills necessary to create and design an outstanding game" while software development teams were becoming more common. COMPUTE! listed the game in May 1988 as one of "Our Favorite Games", writing that the sound effects of the character committing suicide was one of their guilty pleasures. Console XS rated the Sega Master System version 89% in 1992. The ZX Spectrum version was voted the 28th best game of all time in a special issue of Your Sinclair magazine in 2004. Editors have praised it as "the first game that scared me" thanks to its early use of digitized voice and mood setting audio effects. Stuff magazine listed it as one of the 10 best games for the Commodore 64 in their Commodore 64 at 40 article. Legacy The sequel, Impossible Mission II, followed in 1988. It further complicated the quest with new traps and items. Elvin's stronghold also grew in size, divided into a number of towers which the player