Here is a third party version of "Chess" for the Mattel Electronics Aquarius computer. It was created by a company in Europe after Mattel had already paid Radofin to take back the marketing rights to the Aquarius. Although Mattel had developed a Chess game for the Aquarius, it wasn't released until later, by Radofin. I believe that this cassette version was created in the interim, because the prgrammer was not aware that an "official" version was coming. There are some differences between the two versions. Mattel's uses a smaller playfield, which allowed more room on the margins for messages. The pieces in the Mattel version used more of the "prerendered" character graphics, while the cassette version uses more of the low-res "PSET" graphic characters to build the pieces. This approach required a larger playfield in order to make the pieces recognizable. The tradeoff was that that left no room to show the piece coordinates. So, although moves were entered in the same way as Mattels, e.g. "A1 to A5" etc, the letter/number labels were not visible on the cassette version. Interestingly, the Mattel version lists the numbered rows from bottom to top, this version lists them from top to bottom. The alphabet columns are still in alphabetical order in both versions. Ahem. Although this version lacks some features of Mattel's, it also adds some. Specifically, the ability to save and load games-in-progress, is a nice touch. In the video, you can see there is no option for a 0 players (cpu vs cpu). So, I overcame this by pressing the "k" button after every move by the cpu. The "k" button made the players switch which color they controlled. So, essentially, the computer was playing itself, afterall. ;-) Unfortunately, there wasn't enough time in the video to see the game end, but you can tell who's winning.