The battle strategy of Space Invaders is simple: overcome the enemy with huge numbers. Obviously they need a huge army for that, and we’re pretty sure they’re doing mass recruitment from where ever it is that they recruit people. Earth needs to counter the invasion too, seeing that someone is needed to operate the laser cannon to kill all the invaders they can. Here’s the propaganda print to go with the feel. Costs £20 (~$30). Damn the war effort is making things expensive.