1/1000 - First Thoughts and Concepts

So 2 of my friends at school had their first RPG experience a week ago, at our relatively new FLGS by way of a one shot. The theme was zombies. They enjoyed themselves immensely.
Wanting to bank on this, I decided to do 3 things:

1. Offer myself as a GM so they could get drawn into the hobby.
2. Expand out of my High Fantasy zone of comfort by planning to run something with similar themes as to what they played.
3. Allow them to choose what precise theme they would like to play in and then make that one interesting.

So they picked zombies, after my other offerings didn't pan out as far as complexity went. And there I was, then, trying to figure out how to make a zombie scenario interesting. After a day or so of thought, I now have the beginnings of the setting, which I'm naming "1/1000" (as in one thousandth).

1/1000 is a game about a horrible situation. I have taken the zombies theme as "humanity stopped being that, for the most part" and ran with it to other places. Normal zombies are fine, but the drama in the situation will just probably rehash The Walking Dead so I preferred to find my own spin.

One bright day (wherever the campaign takes place it was a bright day) the Change happened. All at once, all of humankind found itself convulsing on the ground and only 1/1000 of the population remained themselves afterwards. The rest? They turned into something near enough to a zombie - they lost most their intelligence and their bodies and senses became stronger and sharper. The Changed, as they are called, are stronger, quicker and harder to kill than any human ever was. Anything that would instantly kill a person before would do so for them too, but short of that, they just keep going. The Changed are cannibals and predators, eating any meat they can chew through.

The remaining humans are stuck in a really bad place - across the globe, they number around 7 million, including those who had died in the first few weeks after the Change. Actual number of the living? Closer to 4 million. Some of the remaining know this, others do not. To complicate lives further, elevation entails an unlocking of unique qualities and capabilities. In humans, it unlocked functional superpowers. Elemental manifestation, psionic powers and other more and less odd powers slowly started activating across the survivors. Every human that hasn't Changed has become a type of superhero, essentially.

So how did this happen? All an act of good will, or so it was intended. A quality humans could not quantify had reached sufficient levels to get on alien radars. Wanting to elevate a whole race to the galactic arena, one alien species made their way to Earth and dropped a bomb that would elevate those who have a sufficient quality and kill off the rest. Progress comes from hardship. Unsurprisingly, as with all things concerning humans, the entire thing was a bad idea. The bomb wasn't meant for humans and where it killed elsewhere, it merely short-circuited the majority and gave a considerably smaller boost then planned to the remainder. The aliens went from elevating a race to doing damage control.

While the Aliens, now with a capital A to signify them as a faction, started on that, 2 other aliens species arrived on Earth after the news of an odd elevation event spread around. One were the Angels, intent on subjugating, with good conditions, the peculiar human race. The other was the Shadows, a gelatinous, amorphous species of hyper-engineered beings. They see humans as an illness and a danger and are intent on our annihilation. Conflicting with the plans of the Aliens and the Angels, the alien species war it out and only a few of them ever come in contact with humans. When they do, the results are interesting.

The optimal way to play in 1/1000 is around your home, after the Change. You know the layout and the area and anything that could be used to some degree. Ideally, everyone playing will stick to a character that shares a likeness to the player and allow for maximum immersion.

Those are my thoughts and concepts behind this. I'm still hammering out some kinks, as well as optimal times since the event in the setting that play is probably the most interesting.

As usual, accepting comments and critiques.