In the late 1970s and early 1980s, handheld electronic games were quite popular. They weren't nearly as successful as later handheld consoles such as the Nintendo Game Boy or Nintendo DS but popular nonetheless. Here are the ones I owned. In fact, I still have them in their original boxes.
Coleco Electronic Quarterback
Coleco Electronic Quarterback was my first handheld electronic game. It seemed like almost every boy had this game. Although Mattel had a football game, I encountered Coleco's version a lot more . It got passed around a lot at school. The gameplay was pretty basic but surprisingly addictive. Coleco also had a Head to Head Football version in which you could play against a human opponent. However, most people had the single player version, myself included.
From the Coleco catalog:
Football game with all the action! You call the plays—kick, pass, run, block. Display shows all the statistics. Electronic sounds and music. Battery not included.



Mattel Electronics Basketball
My second handheld game was Mattel Electronics Basketball. It was another single player game with a computer opponent. I enjoyed it but never played it as much as Coleco Electronic Quarterback.



Coleco Head to Head Electronic Baseball
Released in 1980, Coleco Head to Head Electronic Baseball was an ambitious game. Physically shaped like a baseball stadium, it offered two dugouts with separate controls. Therefore, it supported one or two players. The game even came with a Manager's Handbook as well as an Instructions book. I really liked the game except that it could be very difficult. Trying to hit a fastball was bad enough but it was really difficult laying off of a curve or slider. I suppose it was a lot like real baseball in that respect. My game was bought from local retailer Service Merchandise based on the sticker on the box.
From the Coleco catalog:
One or two player game with all the options of real baseball! You can steal bunt, tag up, hit and run and much more! Computer displays batting average for man at bat—pitcher chooses from 16 pitching varlalions—batter chooses to hIt for average or tor power. Large, bright scoreboard and message center show all statistics and results. Unique sounds and songs, LED lights, and two skill levels. Ages 8 to Adult. Requires batteries or Coleco Battery Eliminator/AC Adapter (not included).



Microvision
One handheld game console that felt very advanced for its time was Milton Bradley's Microvision. I didn't own this one but my sister did so I played it a fair amount. Despite hitting the market in 1979, it supported game cartridges. It featured a black and white blocky 16 x 16 pixel display but they managed to make it work for simple games. My sister had Block Buster and Sea Duel cartridges. Both were very good. The former was a breakout style game while the latter was a ship vs sub strategy game.