GoKawiilBy the late '70s, Nintendo had almost entirely shifted its focus to the video game market, releasing the home consoles TV-Game 6 and TV-Game 15 in 1977, and opening a coin-operated games division in 1979. The same year that division launched, Yokoi was riding the train when he noticed a salaryman idly playing with a calculator to pass the time. That's when inspiration struck: games shouldn't be limited to the arcade and at home, but should be available on the go as well. Thus, the idea for the Game & Watch was born, though bringing it to fruition required a lot of ingenuity.
In a fortuitous coincidence, Yokoi wound up pitching the Game & Watch idea to Nintendo's then-president Hiroshi Yamauchi right before Yamauchi was meeting with the president of Sharp. At the time, Sharp was the world's biggest manufacturer of calculators, and the two discussed a collaboration. The tech behind the Game & Watch is similar to the calculators of the time: both utilized LCD screens and button cell batteries, and achieved their visuals using a system of segments. In a calculator, each number is made up of seven segments, and the number of digits one can calculate depends on the segment capability of its chip. 1980's Game & Watch: Ball was the first in the lineup, and utilized a chip that could display 72 segments.
Game prototyping was done physically first, with a combination of painstakingly-cut acrylic plastic and tiny wheat bulbs placed onto a circuit board matching the size of the Game & Watch. Soon, the team was putting out one Game & Watch title almost every month, releasing 59 total between its inception and 1991. As time went on, the tech improved, first going widescreen before introducing the iconic clamshell dual-screen format seen across other Nintendo handhelds. In total, the Game & Watch series sold over 43 million units worldwide.