Entex

Entex Video Space Battle, Video Space Force and Video Turtles (DVG II series)
(1982, LCD, 4 C batteries, Model# 3077, 3080, 3081)
Case designed by Ortega Orr / Ron Chesley
Electronics designed and programmed by Rick Dyer & AMS

Not quite a self-contained handheld, but these look really neat (and Id love to get one). This was apparently Entexs answer to Atari and such, what you see in the picture is the complete game, you just plug it into your TV and off you go. At least 3 were planned (Video Space Battle (like Space Invaders, seen on the TV here, Video Space Force (Asteroids clone) and Video Turtles). Entex made about 100 of each of these. Im not sure if these were for focus groups/internal testing, or if they were sold in store in test-markets. Either way, they were unpopular and are thus extremely rare, and if they were only used internally, theres a good chance most (if not all) of them were destroyed. This picture is from the 1982 Entex dealer catalog.