Sky Clash is a fun battle game in which you have to save up enough energy to send out the right units and cast the right spells. Your objective is to destroy your enemy's towers before each timed round is over. You can try to destroy all three towers, but you'll already have won each battle if you simply cause more destruction than your opponent does.
Defend your own towers with your orcs and imps, and send them across the bridge into enemy territory. Try to get your orcs to move in close enough to attack the towers, and back up your orc offensive with long-range magic spells.