this is a cowboy moon, he is arrogant sharpshoote gunslinger sheriff,

the asteroids trying to make troubles in his  his beloved's (earth) saloon, he thinks he's so good with his gun he challenge to defeat them all with only shooting over his right shoulder and aiming with a mirror in his left hand, 

use the spacebar to dash in the empty bar space and shot to survive the endless waves of asteroids and planets