The Entex Adventurevision is rare as it is a beautiful vintage gaming machine. Smaller and more compact than the Vectrex, the Adventurevision resembled a miniaturized arcade cabinet, that displayed its awesome but flickering graphics via a spinning mirror and 40 red LEDs. It managed a 150x40 resolution. The console used cartridges and only 50,000 of it were ever produced. As for the number of games released, well, it never reached double digits, though admittedly they were high quality productions.
Happily, you can now find out for yourselves by acquiring this impressive Entex Adventurevision via eBay. It comes with 3 games (and 2 game boxes) including the horizontally scrolling Super Cobra and them intriguing Turtles. Seller ships only within the US I'm afraid.