Handheld electronic games arrived before handheld consoles. A pocket racing game from Mattel in 1976, built around a calculator-style processor and a row of red diodes, sold well enough to prove the market existed. Nintendo's Game and Watch line put inexpensive liquid-crystal panels in credit-card and clamshell cases and sold in the tens of millions worldwide. Milton Bradley's Microvision showed that a portable could accept interchangeable cartridges nearly a decade before that idea took hold, though fragile screens and a thin library kept it short-lived.
The Game Boy settled the argument in 1989 by losing on paper. Its screen was monochrome and unlit while rivals offered color and backlighting, but it cost less, survived a backpack, and ran for a long stretch on ordinary batteries. Color handhelds of the same era drained cells quickly and stayed niche. Later systems widened what portable hardware could do, from a second screen and touch input to console-grade graphics on a wide display, but the underlying tradeoffs never actually went away.
The category now sits uneasily between phones on one side and portable computers on the other. A phone in a pocket removed the dedicated handheld's basic advantage of simply being there, and battery-hungry portables that run full desktop libraries have revived the old argument about power against runtime. Entries here cover the systems, the screens, the batteries and the games that made people carry them, along with the link cables and wireless features that turned portable play into something social.