What is the Air Defense Command game, how does it work?

According to the introduction of Ensit Media, Air Defense Command is a Arcade game on the Android platform. There is currently a 1.2.9 version released on Oct 10, 2019, you can see the details below.

The Alliance is the most powerful military force in the world
They have declared war on us
We cannot win...
... but we must fight!

Engage in a desperate struggle to defend your tiny country against overwhelming odds. Shoot down enemy bombers and exact a heavy price on the enemy's air force.