At the start, click the left side of the screen to change to the previous costume. Click the right side of the screen to change to the next costume. Click the player to start. To move forwards, press the right arrow, A, or click the right side of the screen. To move backwards, press the left arrow key, D, or click the left side of the screen. To jump, press the up arrow key, the space bar, W, or click the player.
I will give @RacingAce credit for the clouds, the graphic idea and the code (except the mobile friendly and WAD/space part). All levels are designed by me.