The trail does not follow you. It fossilizes where you left it, and it never moves again.
Every cell you eat is score, length, and a future wall. Spend length or keep it. That is the whole game.
RUN STRATA BY AGE. NOTHING IS EVER REMOVED.
Every run sheds its trail. The trail hardens into stone, newest bands pale, oldest worn dark. The board becomes a record of everywhere you have been.
The rhino cuts your own stone into glass. Passable. The cell never returns.
And when the board finally closes over you, look at it. You did not lose. You built this.