Iron grid is first person tower defense survival game. You have to liberate earth from alien invasion sector by sector. Your main goal is to setup colossal superweapon called "Iron Grid". Aliens will adapt to your weapons making each encounter more challenging. Unlock new towers based on enemy types you encounter. Construct towers strategically so that aliens cant get to your base. Defend mining stations and destroy enemy monoliths to control sector. Balance between building superweapon components and strengthening your defense.