Tap once to mark a square with X. Your own notes stay separate from the automatic crosses. Auto-cross is off by default. You can enable it in Game settings if you want help excluding blocked squares.
Little lesson 4 · 5 × 5
Click once for X · twice for a cat
Settings save automatically on this device.
Click or tap once to toggle X and blank. Double-click or double-tap to place a cat. Click a player cat to remove it. The starting cat is fixed.
Keyboard: arrows move focus; Enter or Space once marks, twice places a cat. Holding a key does not repeat a move.
Undo reverses your last move. Hint explains a deduction or highlights optional candidates. Reset clears your moves and keeps the starting cat.
Any complete arrangement that satisfies all three rules wins. There may be more than one solution.
Clear this board and its notes. The starting cat and completed levels stay safe.
Nicely done. Every cat has found its place.