Ixion is an unreleased arcade game based on Sega Zaxxon hardware, developed by Sega Electronics set to be published by Sega in 1983.
Ixion is presumed to have failed its location test, i.e. it was largely finished and put into use in small quantities, but poor consumer feedback and/or low profit margins stopped Sega from producing more units. The arcade game has been dumped and is fully playable.
Plans for Ixion appear to have been quite significant. As well as working on an arcade version, Sega Electronics created versions for the Atari 2600, Atari 8-bit line of computers and the Commodore VIC-20, each of which were subsequently cancelled. Two versions of the 2600 port exist, one by Jeff Lorenz (subsequently released online) who was responsible for several arcade-to-2600 ports for Sega Electronics, and another by Stance Nixon under contract. The 2600 and VIC-20 ports were set to be released in 1984.
The Atari 8-bit version, developed by Fred Mack has also been released online - this version, copyrighted 1985, credits U.S. Gold, suggesting it was to be published after Sega's temporary pull-out of the US market.