A world scale alien invasion is happening. To invade earth, aliens started war against humankind, but they are not trying to destroy the earth's surface. They are not shooting their weapons to earth, But trying to land on earth first and deploy their army. The military is trying to control the alien army by terrestrial combat. Aliens are trying to land their ships on earth. Your Mission is to prevent the alien ships landing on earth. Remember... The last air defense is You... Good Luck Captain...