Closed Loop, a 5x5 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
No patch is certain at the start. The tall clue in the top-right corner gives no size, and it turns out to be by far the largest patch on the board. Work inward from cells that only one clue can reach: the 2s in the left corners, the two 4s in the middle columns, and a wide 3 across the middle that keeps the top and bottom halves apart.