Post
Your character's position is more precise than what the screen shows, and those invisible decimal places determine whether a trick works or fails.
Games track player position using floating-point or fixed-point numbers that have far more precision than the pixel grid on screen. Your character might appear to be in the same spot visually, but internally their X coordinate could be 142.3 or 142.7, and that 0.4 sub-pixel difference determines whether a jump reaches a platform, a clip works, or a zip fires in the right direction. Runners learn to control sub-pixel position through specific movement sequences: walking a precise number of frames in one direction, tapping against walls to align to known positions, or using in-game items that set exact coordinates.
Example
In Super Mario Bros., the flag pole glitch at the end of World 1-1 requires Mario to have a specific sub-pixel X position to clip through the base of the flagpole. Runners use precise acceleration and deceleration patterns throughout the level to arrive at the flag with the correct invisible decimal value.
Why it matters
Sub-pixel positioning reveals a layer of game state that's completely invisible to normal players. Understanding it separates good speedrunners from great ones and shows that what you see on screen is a simplified representation of a much more complex simulation happening under the hood.
Related concepts