9. Atari Cosmos
In many ways the Cosmos is the strangest entry in this list, not just because it was a conventional games console, but also because it was cancelled after it had gone into production.
A handheld that used holographic technology to achieve a 3D image, the Cosmos' screen was a fairly standard LED display, as you saw on many of the standalone portable games of that era. But by putting on a clever overlay, the system would produce a holographic image. Each of the nine games would consist of both a cartridge and an overlay to put on the screen.
Atari showed the system off at the 1981 New York Toy Fair and secured over 8000 orders from retailers off the back of it, despite some very critical reviews from the press. The system was advertised heavily in magazines of the time too, and even went into full production before it was abruptly cancelled without ever being shipped to retailers.
Rumour has it that bosses at Atari were worried about the critical reception, and the influence it might have on sales of their hugely successful Atari 2600 console.