Games were available in cartridges with a ROM chip containing the code (program) for the game. In total, around 70 games were officially released, and there are some “new” games that were developed by hobbyists that can be bought online. Virtually all games developed by Magnavox/Philips have an exclamation mark at the end of their names.
There were two kinds of packaging for the cartridges: cardpaper, used only in the United States; and plastic with an acrylic lid, used in Europe and Brazil. For each game there were two sets of artwork for the cartridges: the “American,” used in the U.S. and Brazil; and the European. In Figures 15 and 16, you can compare the two styles of boxes for the cartridges.
The first cartridges used a 2 kB ROM, but later games used bigger ROMs. (The system supported up to 8 kB ROMs.)
One of the main problems with the Odyssey2 was that Magnavox/Philips decided that it would be a closed system and wouldn’t allow other vendors to develop games for it. Therefore, most of the games were developed by only a handful of people. When the company decided to change this rule and allow other vendors to port their games to the Odyssey2 (in particular Parker Brothers with Frogger, Popeye, Q*bert, and Super Cobra; and Imagic with Atlantis and Demon Attack), it was too little too late, and the Odyssey2 was hit hard by the Video Game Crash of 1983. (In Europe and Brazil the crash occurred later than in the United States.)