Start gate
Finish gate
Corridor walls
Every UI element you slide a cursor through — a scrollbar track, a nested drag-menu, a stylus gesture channel — obeys the steering law, not Fitts's Law: difficulty accumulates continuously along the path instead of resting on one target's size and distance. This bird's-eye 2D simulator renders a winding corridor whose width and curvature you control, lets you steer a puck through it with the pointer, and integrates the corridor's true Index of Difficulty (ID = ∫ ds/W(s)) from its exact plan geometry. A live width-profile graph beneath the main view shows the local width and difficulty density along the whole path, so you can see exactly where the corridor demands the most control. A run only counts if the puck stays inside the walls from the green start gate to the red finish gate; your measured movement time is then compared live against the steering-law model's prediction (MT = a + b·ID, with both constants tunable) and converted into a throughput figure in bits per second, the same metric HCI researchers use to benchmark pointing devices.