Williams Electronics‘ 1982 arcade classic Joust sees you atop a flying bird, trying to knock other riders off their flying birds.
The trick is to bump into them at a slightly higher altitude than they are, otherwise they will knock you off.
Joust is a simple, early arcade game, but with refined controls, nice, crisp graphics, and infuriatingly addictive gameplay. Which makes it fun to play even now.
More: Joust on Wikipedia