DOH! I forgot, but I shouldn't have.
The original Magnavox Odyssey had a whole ton of materials without which most of the games would be useless. Either Cards, Overlays, Gameboards, Tokens. Hell, even the instructions were absolutely necessary because the "videogame" part was in no way intuitive. You really don't know what you're supposed to do unless you've got a manual telling you what's going on.