I will always admire the Japanese.
Today, it's those guys at iGem Osaka
Definitely an interesting take on pixel art. They did this using genetically engineered glowing bacteria.
Seems like they manually laid out the two colored bacteria in a grid, and then grew/stimulated them individually to get each to expand within their cell.
I particularly like the irregularity of each cell, giving great variety to an otherwise rectilinear art form, yet still keeping that nice retro feel.