Puzzle select
Drag on the board to draw ramp ink · start each ramp a little behind the stream · fill every cup to its white line · P pours · U undoes · keyboard? Tab to the board, arrows move, Enter sets each end of a line.
01 · INK
02 · POUR
03 · CUPS
HOW THE SAND BEHAVES
- Each grain falls straight down; if blocked it slides one cell diagonally.
- The stream is three cells wide: each grain leaves the spout up to one cell left or right of centre, so start a ramp two or three cells behind the stream or grains will miss its top end.
- Grains creep along slopes as shallow as one cell down per two across; flatter ground holds piles.
- Walls, cups and your ink are leak-proof: sand never squeezes through a corner.
- Sand that reaches the bottom edge is lost.
- The daily puzzle is built from the UTC date, so everyone gets the same board. Before you see it, the same simulation checks that it can be cleared within the ink and that one plain ramp per spout is not enough.
- This is toy physics — a small cellular automaton made for the puzzle, not a model of real sand.