The Videomaster Superscore (model VM-8) was released in 1976 and sold assembled or in kit form (to be fully assembled). British advertisements were put in magazines such as Television Magazine. Few commercial systems were proposed in kit form. This model was pretty well designed since the customers could order different types of RF modules (UHF, VHF) to adapt the system to the existing television formats. It was sold in several forms: Superscore (the game unit), Superscore Plus (game unit and electronic gun), and Compendium (a nice carton carry case containing the game unit, the electronic gun, the AC adaptor and the additional paddle allowing both players to play without sharing the main unit).
Without the electronic gun, the unit coud play four games: Using the electronic gun, two more games could be played. Amazingly, they were called AUX1 and AUX2 (as "Auxiliary 1" and "Auxiliary 2"). This was obviously done to show that these two games were only playable with the optional gun.
Further information can be found at http://www.pong-story.com/vm8.htm