Put an alien in every empty square till you fill the whole board. But be careful! You must avoid 3 adjacent same colored aliens (horizontally, vertically, or diagonally).
Some squares are fixed and you are not allowed to put an alien there. But use those squares to your profit. You know, sometimes creativity need constraints ;-)
Original idea by Erich Friedman. Each puzzle has a unique solution. All puzzles © Erich Friedman, 2010.
Art by Kenney and Freepik.