Invasion! is a sci-fi arcade shooter, inspired by the classics of days gone by. War between the Reds and the Greens has been going on for millennia, and now, in the closing moments of the war, the Reds are bringing it to home soil. Defend your green brethren from the invading Reds, under the tutelage you ever inspiring drill sergeant. Use a wealth of supplies in battle to thwart the wretched enemy and claim victory for the Greens, once and for all.