I found these games a few months back in a lot. There seems to be very little info on 5200 Activision prototype carts, so I thought I would share my find. - All four games were found together in a large 5200 lot I bought on Ebay. When contacted, the seller just said that someone told them they were replacement labels, but they were not the original owners. - The games *seem* to play exactly like the retail versions, but I haven't actually dumped the ROMs. - Kaboom, Pitfall and River Raid have a blank reddish label similar to Activision protos for other systems, with a white typed label stuck on top. Dreadnaught has no label except for the white typed one. - The cartridges don't have a clip at the top like other Activision games. The texturing that you see on retail Activision cartridges isn't on the proto carts, which feel much smoother. The pictures show comparisons between the proto and retail carts. The exception is Pitfall, which has a textured top half and a smooth bottom half. The cartridges also had sticker residue on the back when I got them, so I'm thinking maybe the back had a label or they reused cart shells. - The only one I could safely open was Dreadnaught, which had an EPROM inside. That's the one shown in the pictures. I didn't know about the EPROM UV light thing at the time, but yes, I have since been educated as to why I should have covered the window =) The game was tested after being put back together, and it still plays. Does anybody else have any carts like this, or any more info? I haven't quite decided whether I want to try to get a full set or just keep one or two, because I can't find any other copies anywhere. All I see is one thread from years back here on AA where somebody found three or four.