Space Invader 2 came with the system. In late 1981, Entex was sued by Coleco, which held the licensing rights to handheld versions of Pac-Man at the time, for copyright infringement over their upcoming release of Pac-Man 2. The game was pulled shortly after release as part of the settlement. Because of this, Pac-Man 2 is the rarest game released for the system. The game cartridges play very similar to their hand held counterparts (Entex made quite a few hand held games such as Space Invader 2, Basketball 3, Pac-Man 2, etc).
The Select-a-Game used a 7 x 16 vacuum fluorescent display (VFD) array of large dots as the main display. It could display two colors, red and blue. These were combined with static overlays for each game. Together they made the display. The system was basically a display and controller for the games with no built-in processor power. Each game cartridge contained a microprocessor programmed with the appropriate game code in it. In this respect, it was very similar to the concept of Milton Bradley's Microvision system released a few years earlier.
The system could be powered by 4 C batteries, or by an external A/C power supply. The power supply was only available by mail-order, and as such is exceptionally hard to find today (but a common universal A/C adapter will work with the system).