Joust

"Joust is an arcade game produced by Williams Electronics in 1982, and ported to numerous platforms.

The player controls a knight armed with a lance, mounted on either an ostrich (player 1) or a stork (player 2), who battles waves of computer-controlled enemy knights mounted on giant buzzards. These knights have three different speed and agility levels. The game screen is static; its only features are five platforms hanging in mid-air (some wrapping around the screen), the ground, and a pit of lava beneath.

A joystick moves left and right, and a "Flap" button flaps the mount's wings once. Pressing "Flap" in rapid succession will produce a gain in altitude until simulated gravity drags the mount downward."

Source: Wikipedia, "Joust_(video_game)," available under the CC-BY-SA License.