Simple Puzzle Game: Switcher

The gear have two states, red and black.
When you tap a gear, the state of the tapped gear and its up, down, left, and right gears are reversed.
If all the gears are turned black within the time limit, the stage is cleared.
In the "Hard Mode", there is a limit to the number of taps, and the game is over when the number of taps reaches 0.