OMG SPOILERS!
The guy is in a spaceship that was hit by an asteroid and before he dies he has four chances to see the past.
The blue is his city, before the war. Look how it is getting polluted.
The white is the city, after the war. It's not snowing it's a neucular winter.
The red is an alien's corpse from the human-alien war.
The green is earth exploding from alien missles.
And the end, he escapes the spaceship and flies into the sun, ending the human race in a selfish way, Self Delete.