Germs are invading your tiles! Only Altro WhiteRocks can help! Blast your rocks at the breeding germs before its too late! Cover the majority of the tile surface with WhiteRocks to proceed to the next level. But beware - you only have a limited number of rocks to fire and your time amount will reduce on every level, so you'd better be strategic about where and when you fire your rocks!
Use your mouse to move the target. Press the mouse button down to start the power and release the button to fire the rocks!