A pile that reaches 4 grains topples: one grain goes to each neighbour. Grains that slide off the edge or into a pit are gone. Match the target garden with as few drops as you can.
Tap or click a cell to drop one grain. On a keyboard use the arrow keys to move and Space or Enter to drop. U undo, R reset, H hint, N next level. Toppling cells fire together in waves, but the final garden never depends on the order of your drops, only on how many grains you put where. That is why the par is a puzzle about counts, not timing. Par is the exact minimum, found by checking every combination of drops. Stars: par or better is 3, one over is 2, otherwise 1. Using a hint caps you at 2.