Xonox was one of the companies who entered the video game market with low quality games. However, they are the only one that created double-ender cartridges for the Colecovision. They could be inserted into the console on one of the two ends, each end offering a different game. Xonox eventually abandoned this idea and began releasing single versions of some of their titles previously offered as double-enders as well as a few new titles.
A total of twelve cartridges have been released by Xonox for the Colecovision : Three are double-ender and nine are single games. All the games are relatively rare, espicially two of the double-ender which are the rarest games in the Coleco’s system.