Drag from a dot to the other dot of the same colour to lay a pipe. Pipes can't cross, and together they must fill every square. Solve as many puzzles as you can in 60 seconds — every one is new.
2 puzzles solved at a level moves you up; 2 skipped in a row move you down. The grid grows from 5×5 to 8×8, and fewer colours on the same grid means longer, twistier pipes. A solved puzzle earns its number of squares + 4 × the level.
Every pipe changes the room left for the others. Seeing which routes would trap another colour — before you draw — is spatial planning and foresight.