Fill

a stroke that can't stop halfway.

pick up the marker and drag it a direction -- it runs until it hits something. fill the whole sheet without sealing yourself off

A slide here cannot stop where you want, only where the wall is, so the move you make first is the one you can least take back. Working backward from the corner you want to end in -- and only then figuring out what gets you there -- beats reacting one slide at a time. An early slide can also wall off a stretch of paper you can never reach again, which is the whole trap: not a bug, the point.

Concepts: planning, constraint, commitment.

An interactive you play with one thumb, on Wundr.