Each puzzle starts wrong. Edit the grid, press Drop, and let the physics decide whether the floor reads what was asked.
Liminal runs whatever settles. Pieces fall and stack — on walls, the floor, and each other —
and the settled rows that begin with let or print are the program,
read bottom-up. @[r,c] reads a single cell of that grid. A puzzle is solved when
your arrangement, once dropped, prints exactly the requested line.