Pacman

The maze game that defined the arcade, playable in a browser with no quarters involved. You clear a maze of dots while four ghosts pursue you, and the power pellets in the corners briefly reverse the relationship — which is the entire design, and it has survived four decades because the pursuit is not random. Each ghost behaves differently. One chases directly, one aims ahead of where you are going, one approaches obliquely, and one moves erratically — and knowing which is which turns the maze from a panic into a geometry problem. Experienced players do not dodge; they route, using the corners where ghosts lose ground on turns and keeping a pellet in reserve for the moment the maze gets crowded. That depth is why it still rewards attention. The early mazes are an introduction, the speed rises, and the skill that carries you is pattern knowledge rather than reaction time. It plays with four inputs, works on a touchscreen with swipes, runs on anything, and gives up its basics in thirty seconds while taking much longer to actually play well.