Yes, Halo is a real game.
No, the year is not 2552, we are not fighting an array of different species of aliens who banded together under a religion that believes in worshipping an extinct alien race which annihilated all life in the galaxy and then replanted that which they thought was worth keeping, Voi and New Mombossa are nor really erased from the earth, there isn't a Forerunner artifact several miles beneath the two cities, and no, there are not giant rings of death floating out in space with the capability to annihilate all life with just the touch of a human hand.
Has Bungie created an extensive and awesome backstory for the game? yes. still isn't real.
unless you mean halos above angels' heads, and that depends on your religion, and the question wouldn't belong here
Yes master chief is gonna save us all. In other words no.