Mattel / INTV Games
Since Mattel is the company who made the Intellivision game system, it's just logical that the company would host the most games. This lists includes the games made by INTV, which took over for Mattel towards the end of the Intellivision life. These games are much harder to come by and have fewer variations. Many of them did not have overlays made. Below is a link which shows the major differences in the cartridge itself, not the labels. Please understand what you are looking for if you collect variations.