Look to play
Breakout, steered by your eyes. The paddle follows where you look; pinch your thumb and finger to launch. Everything runs in this tab — the camera feed never leaves your machine.
If the paddle is off, calibrate — and go fullscreen.
The tracker reports where you are looking on the whole screen. This playfield is a box inside a page, so until it is told otherwise it has no idea that the left edge of the game is not the left edge of your monitor. Fullscreen removes that gap; Calibrate measures whatever is left, including the part that is simply you not being the person the model was trained on. It takes about seven seconds and is remembered in this browser.
Expect it to be worse for you than it is for me.
The model shipped here was trained on one person, at one camera and one screen — about 19,600 frames of a single pair of eyes. Cross-person webcam gaze is a harder problem than cross-session, and a stranger should expect roughly a few degrees of error, which is a couple of hundred pixels at normal viewing distance. Breakout survives that because a paddle needs only one axis and you correct it continuously by watching it. A mouse cursor at the same accuracy would be unusable — which is exactly why this is a game and not a pointer.