BirdDuko

Every colour patch hides one bird. Work out where they're sitting! Birddoku is a calm logic puzzle: place one bird in each colour, never two in the same row or column, and never two touching, not even corner to corner. Boards start at a gentle 4x4 and grow to 9x9, with new levels that keep coming.

Tap a square once to cross it out. Tap a crossed square again to place a bird. Tap a bird to remove it. Drag across squares to cross out several at once.
Rules: one bird per colour patch, one per row and column, and birds may not touch, even diagonally.
A wrong bird costs a heart; lose all 3 and the level restarts. Use Hint to reveal a bird and Undo to step back.