The score you get when you connect a moving crosshair to a stationary target without drift, without overshoot, without second-guess. Measured in hit rate, time-to-click, and arc deviation across 60 variable-size trials.
Worked example with illustrative numbers: a score of 82 on Aim reflects hitting 92% of targets inside an 800ms deadline across 60 trials, with an average arc drift of 0.18°.