Researchers in Norway built a 1mm wide Pac-Man board and populated it with single cell organisms.
From PopSci
You can’t control them, but it’s fascinating (and a bit creepy) to watch Euglena, ciliates, and rotifers wander around the oh-so familiar maze. While the video might give you a creepy-crawly tingle, worry not: there are probably far more microscopic creatures on an old arcade joystick from the original Pac-Man than you could possibly fit in this mini maze.