In 1972 Atari released Pong, a game screen of just 192×160 squares. The designers had no choice — they could only fit the ball, the paddles and the score in with the fewest possible pixels. This was not an aesthetic choice; it was a hardware limit.

But constraint breeds style. When Super Mario Bros shipped on the NES in 1985, Mario wore a hat because 8×8 pixels couldn't draw hair; he had a moustache because they couldn't draw a mouth. Nintendo's designer Shigeru Miyamoto turned every limit into personality.

By the 16-bit era (Super Famicom, Mega Drive), pixels could render a more delicate palette-constrained aesthetic — Zelda, Final Fantasy VI, Chrono Trigger. Then 3D graphics arrived in 1996 and pixel art 'died.'

But in 2009 Minecraft brought pixels back to the mainstream; in 2016 Stardew Valley, Celeste and Undertale proved that when you stop caring about technical show-off, pixels are the medium best able to convey 'heart.' Today they are the carrier of choice for indie games, emoji and every 'retro' mood.