Reportedly, Atari had a programmer working on a Commodore 64 version of Stargate when the industry crash compelled the company to cancel most of its remaining AtariSoft projects. Nobody knows how far along Commodore Stargate was at the time of its cancellation. No prototype has ever been found, and indeed, the only evidence the game was even started is a picture taken at the 1984 Consumer Electronics Show, where a sliver of a monitor purportedly showing Commodore Stargate can be seen.
A couple of years following the industry crash, a game claiming to be AtariSoft's Stargate for the Commodore 64 began circulating through the pirate community. Had Stargate escaped prototype purgatory the same way the AtariSoft versions of Mario Bros. and Crystal Castles did? As it turned out, no, that wasn't the case. Despite AtariSoft's name on the title screen, it is apparent this Stargate is the same as a Commodore 64 game called Guardian. Guardian is a very well-done Defender clone, so well done in fact that Atari might have sued Guardian's publisher had the game come out at the same time as all the Pac-Man clones Atari took down in the early 1980s. Some have speculated that Guardian's programmer, Steve Evans, was working on Atari's Stargate, and when the project was cancelled, he took his code with him and later released it as Guardian. That theory doesn't explain why Guardian has everything that Defender originally had, with none of Stargate's embellishments. Of course Evans might have stripped those embellishments before releasing Guardian but then why would he bother also releasing the "original" without putting the embellishments back in? The more likely explanation is, someone simply hacked Guardian's title screen and then pretended it was a long-lost Stargate prototype.
A good Defender clone like Guardian can certainly offer a solid foundation for a good port of Stargate, but it takes a lot more than a new title screen to pull it off. For that reason, this alleged Stargate just isn't necessary. Play the actual Guardian instead.
Grade: C-.