After a time of relative peace… and boredom... the heroic protectors once known as Sentinels have been called back into action! Use the unique skills of Sam, Kat, and Frank to lay waste to the seemingly endless horde. Deploy powerful automated towers, upgrade them to devastating Elite towers, and watch the mayhem. When that doesn’t quite cut it, rain down meteors and acid attacks with manually activated tactical weapons. And of course, because you love to get your hands dirty, you’ll be jumping into first person shooting mode, sniping and blasting your more dangerous foes.