Mattel's Computer Gin II (19--, LCD, 9 Volt, Model# --) (Prototype, never produced)
Yes, the picture below is just the normal Gin game, and that's exactly what the only known prototype of this game looks like becuase it was built into an existing Computer Gin case at Mattel. The only visible difference are a couple of different sprites on the LCD panel (I will try to get a photograph of the actual prototype with one of these lit up, but it's not easy... :)
Story: Apparently the released Computer Gin doesn't really play Gin perfectly (I don't know the game, so I can't verify this). There's certain things you can't do (basically, it wasn't designed very well, primarily becuase Mattel wanted to get it out in time for the Christmas season), so they finished as best they could and released it. Later, a new programmer was hired on, and one of his tasks was to develop a Gin II that played the game properly. He finished this, and built the only prototype believed to exist using a shell from a normal Computer Gin. Mattel decided not to continue with it I believe due to lack of sales of the original unit. (This info is sketchy, I'm trying to remember a conversation I had several months ago... I'll be updating this more details soon.)
Do I have this? No (never produced).