I started reading this and thought it sounded amazing, but coming up to the part; "One of the attackers said to him,"Don't worry child, black rain will come." So a few years later, Connell is in the marines and is in conflict with the War Oracles. The leader of the War Oracles was known as Abdul Reneir (pronounciation-Ray-nair). His belief was to dominate the world and promise his people that he is the true leader of the world" you lost my interest. It honestly sounds to cliche.
This whole thing sounds too simple with too few secrets and single player thought, that and you've put more thought into multiplayer modes then you have single player stuff. It's like when I played the Battlefield3 campaign, it started out reasonably okay but then everything became too obvious - it was just countless excuses to make me shoot more stuff in different ways. It was like a massive tutorial for the Multiplayer- the game was pretty much only made for that.
I think you need to put more thought into your OWN universe for the game to go in, not try to squeeze it into ours and make it sound believable! That's how some of the best names out there get so famous- Halo, Mass effect, Star wars, Assassins creed - they all came up with a universe that they could bend to their will and make fit in any way possible.
Assassins creed does try to fit our world but at least they don't go too realistic, they change history, add stuff to it, they have a thick storyline in there with loops back on itself and connects together in ways the player cannot begin to fathom. In yours it just seems like a guys parents get killed, he swears revenge and you find out the motive behind the attack later.
WHAT I WOULD DO:
On top of that think WHY would they go after him anyway, jeapordising their plan by leaving a witness as well as wasting resources over a simple death - would a world leader bent on making his country the best actually do that?
I think you should add a darker, weirder layer to it. How about he is part of a cult, not a world leader but a terrorist organisation. Maybe they worship some other-worldly thing called the 'Black rain'. You would try making them act all insane only to find out later in-game that the Black Rain is controlling them all and planned it out.
Maybe this not-world-leader isn't even leading anything but secretly working behind the backs of his cult leaders, but they're all being controlled and the Rain saw them as getting in the way for some reason and decided to make them destroy each other.
Oh and another idea!! These just keep coming! At the end of the game the main character thinks he's defeated it but in fact gave into the reality of it's existance and goes insane or becomes controlled himself. If you go on an emotional journey throughout the game you get attached to the character and MORE SADNESS.