Click to select one of your own (yellow for the agile race) buildings, holding and dragging to select multiple buildings, and then drag the arrow to the building you want to attack. Half of your troops from all selected buildings will move to attack the selected building. Spawn buildings will regenerate troops, while towers will not but will attack approaching enemy troops. Capture all of your enemies' (blue or red to start) buildings to win each level. Gray buildings are neutral and will not attack (unless you approach a gray tower) and do not need to be captured to win a level. As you kill enemies, your energy bar will fill. When it is full, press A and then click an enemy building to destroy half the troops in that building.