The description names two changing features
Paint over the lines explicitly says both the number of runners and the geometry of the lines change. Those variations mean a plan based on the last arrangement may no longer fit. Before acting in a new scene, identify how many runners are actually present and which line belongs to each one, where the interface makes that relationship clear.
Trace before combining actions
Follow one visible line through its turns and crossings. Then inspect how it relates to the other lines in the current layout. A crossing can be visually important without proving a collision rule; read the actual instruction before deciding what interaction must be avoided or coordinated. The excerpt stops before explaining what each little character does, so the line geometry should prompt questions rather than supply undocumented answers.
Check what changed after the attempt
If an action produces an unexpected result, compare it with the current arrangement, not a remembered easier scene. Did the runner count change, did a route bend differently or was the input misunderstood? This note gives no timing schedule or tested level solution. It offers a scene-reading habit grounded in the two variations the supplier actually names, while leaving start controls, completion conditions and runner interactions to the running game.