Air control
How much a player may steer their character while airborne — physically absurd, but essential for a platformer to feel responsive.
In reality you cannot change direction mid-jump; in a platformer you almost always must, or every misjudged leap feels like a punishment. Air control is the parameter that sets how fast the character's horizontal velocity may change with no ground contact — from full Mario-style steering to heavy momentum where the jump is locked once it leaves the floor.
The value is tuned by feel, not physics, and interacts with coyote time and variable jump height. Pushed too far one way it became Quake's air-strafing, an accidental but beloved bug in which skilled air steering lets a player accelerate past the ground speed cap.