Well, thank you Mathgrant for getting me interested in this...
So I was looking at the TV Play-Along Wheel of Fortune and trying to figure out how exactly it worked. I recorded a video of my methods and progress (which wasn't a lot) and I may be looking into a better way of capturing the VHS cassette.
If you don't want to watch a video...
From the owner's manual of the Wheel of Fortune game unit, we can pretty much guess that it's using some kind of optical encoding. It'd be easy to do at the time (as per NES Zapper). I would think that maybe using audio would work better but that wouldn't be reliant on distance from the screen, screen size, etc.
I went on Ebay and I couldn't find the darn game unit. I would love to take a look at the electronics inside of it and maybe even get a dump of the ROMs inside.
I'm guessing it's going to be a Z80 based unit, since that was popular at the time for embedded solutions and low-cost computers. I'm also expecting the data to be full ASCII text, with probably a start and stop bit and perhaps some kind of checksum.
Alas, I do not have this unit. All I have is the Volume 2 tape from the game. For some reason this was being listed on Ebay as a new and unopened package.
The glue on the outter package was very degraded and that package just fell apart. However the tape inside was wrapped in plastic still.
I captured the VHS tape using a Sony SLV-N51 and a Diamond VC500 capture card. Since the SLV-N51 only has a composite video output, the resulting video has some chroma waviness.
This video is about half an hour long and is the full cassette. I'll have to capture it again later using a higher end VCR and the S-Video input on the capture card.
So we know that we're using optical encoding of some sort, and I'm expecting there to be something flashing on the screen that the game is actually looking for.
According to the instructions on the tape, you're supposed to wait until it shows the puzzle number and clues, and you type the puzzle number into the game pad. It seems that the encoding starts at that point.
So these three frames are a little ways into the footage from when the puzzle number and clues first appear, and so starts the ultimate game of "spot the difference".
As you can probably see, there's nothing really obvious.
So that's as far as I can get without knowing exactly what the game pad is looking for. Theoretically, if you knew what it was looking for, you could make something else (perhaps an Arduino with a light sensor) to just output the solution to the puzzle and cheat.
So, beyound that, I don't know. If anyone has one of these Wheel of Fortune units and doesn't have the Volume 2 tape, let me know and maybe I can send it to you for your amusement.