Practice
Practice sets.
Seventy-two ponds with no date attached, three sets of eight per level. They never change, so you can come back to one, and they do not touch your daily streak. Your progress in each set stays in this browser.
Easy.
Eight by eight. Every pond here opens with the plain steps Hint knows: a line whose number is reached, a tree with one free cell, the eight cells around a lodge.
Medium.
Ten by ten, and each pond needs a couple of the harder steps: fitting a whole line at once, or ruling out a cell that touches every place a tree's lodge can go. Hint shows how.
Hard.
Twelve by twelve. More trees, at least five of the harder steps in every pond, and trees that share their free cells.