Ambush is a unique take on the tower defense genre. Instead of building turrets that automatically fire at enemies, you will have to instruct your units when to fire. Once your units fire, the enemies will shoot back. You can also launch airstrikes to assist your units in combat. Units and airstrikes require reinforcement points, which are earned by killing enemies. You'll also earn upgrade points that can be used to unlock new units/airstrikes, upgrade unlocked units, and increase your starting number of reinforcement points.