I asked a question recently about the Nintendo PlayStation, a prototype for the unreleased SNES-CD periphreal. There was some question as to whether or not a question about a canceled console (or game for that matter) was on topic for the site.
The closest precedent I see is Are questions about unreleased consoles on topic?, but that is more about consoles that are going to be released in the future (e.g. asking about the next PlayStation console and its games before the official release date). The consensus was to close such questions because they are speculative until public release.
However, that rationale doesn't seem to apply for the Nintendo PlayStation here because, although it was canceled, the only known prototype is available to the public in that its existence and capabilities have been extensively documented. Moreover, the physical prototype is currently being toured at conventions. I could see a similar situation with games; perhaps a game was canceled but years later the developer released the source code or it was leaked.
Are questions about canceled games and consoles allowed if they are now accessible to the public?