You got limited time to take out all targets. The white bar indicates how long you have to complete the mission. The red bar shows how long before snipers zero in on your location. Shoot them down before they get you!
Take control of 16 different units and 15 different turrets to defend your base and destroy your enemy. You start at the cavern man's age, then evolve. There is a total of 5 ages each with its units and turrets.