QWOP

Historical relevance. Its still pretty fun. Still hard as heck.

The miracle of QWOP is how quickly it teaches you that having four keys for four muscles is technically more control and practically much, much less. A few seconds in, running starts to feel like an advanced academic subject.

It also earns its reputation. This is one of the browser games people still name years later, partly because it was early and partly because face-planting twenty centimeters from the start line is a timeless comedy format.