Practice
Practice sets.
Seventy-two lairs with no date attached, three sets of eight for each 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.
Five by five, four foxes. Every clue here can be read on its own: write a fox where it can be, and a fox with one cell left goes there.
Medium.
Six by six, five foxes. Clues start to link two foxes, and the chamber of the lost thing starts to matter.
Hard.
Seven by seven, six foxes, more clues that link and fewer that place. Nothing here needs a guess either.