Defeat the Gigant Edge mini-Boss in the Royal Road 1-1 level. Then move to the far right and fly up to find a path made of stars. Follow it until it ends then look up to see a crescent moon. Fly up to the moon and press Up to enter its opening. You are now in a secret testing room that has the HAL logo made from blocks, an enemy, and several ability options. Destroying the blocks will reward you with extra lives.