Airstrike is flashback to childhood with pen and paper, when you were imagining enemy soldiers advancing mercilessly to your Headquarters, and you have a plane and a bomb to defend it.
You have 3 types of bomb, 3 sizes, with every hit you get one more bomb. Every few hits you got one bigger bomb at your disposal, and with more hits, even bigger bomb.
And that’s it, pretty simple when you look at it. Just defend HQ as long as you can. Remember you have a plane and a bomb, you can’t let them win.