1. Blue can move only 1 square at a time.
2. Yellow moves like a rook until it hits a wall or goes off the board.
3. Red cannot move, but acts as a block. Tapping on it removes it.
4. The Blue/Yellow square reverses all the colors.
There are 45 levels. I'd like to see a 'Level Builder' where users can make their own levels for others to solve.
Dotless is very very good. It's free and fun and challenging. It's a little gem.