Loom Work, a 6x6 Patches puzzle
Arrow keys move. Enter starts a rectangle; arrows resize it; Enter places it. Escape cancels. Delete removes a patch. Control or Command Z undoes.
About this board
Nothing is fixed at the start. The 9 in the centre has three ways to be a 3x3 block and the tall 8 on the right has two, and the cells all of their options share are what get things moving. Two placements, the wide clue in the top-left corner and the wide 3 on the right, are settled only because the alternatives would strand a neighbour, and the tall clue down the left edge needs a second round to pin down.