Destiny is a blend of MMO and FPS, developed by Bungie, the same group that brought you Halo. It’s got the incredibly satisfying core gameplay loop of Halo, but it’s tied to a loot system that’ll keep you entertained until the sun goes supernova. You assume the role of a Guardian, and travel between different planets in our own solar system, completing missions, free-roaming, and taking part in the game’s Strikes and Raids.
The Red Legion faction of the Cabal, have attacked Earth's Last City in overwhelming force. Dominus Ghaul, their commander, believes that the Traveller - Destiny's iconic big white orb - made a mistake in transferring its powers to you rather than him. He's out to convince it to change its mind, seemingly by holding it hostage on a big ship in the center of his fleet. If your powers are transfered, you and all the Guardians will lose the power. You lose your gifts and stagger, defenceless, away from the fight. This explains why Ghaul wins - he's organised, and has his stuff together.