Sorry I'm late! Sorry I'm late!
Not college classes on weekend, but some family business to attend to.
*ahem*
Well, I was going to go with aliens in any case, but this was the idea I had in mind (the really short version):
Spoiler for Hiden:
Basically, an unknown energy source is discovered on Earth, and soon, people begin fighting over it. However, an alien race looking for the same power source comes in and tries to take it away, so the two factions put away their differences to stop them. However, it's eventually revealed the aliens actually wanted to get rid of the energy source, because it attracted the attention of an intergalactic locust swarm (so to speak), which is now making its way to Earth. Not helping matters is that one of the aliens actually wanted this, as he wanted to obtain control of this swarm. And so, the others team up, defeat the evil alien traitor and his lackeys, and defeat the locust queen once and for all. Cue the epilogue.
Not the most original, but it can be worked with.
Not a bad idea at all.
But I don't think it's possible to outline the whole plot for what is essentially a free forum RP.
It'd develop naturally. And unexpectedly.
Anyways, like I said, this is a good setting.
So what would be that certain energy source/mineral/whatever everyone is fighting for?
You have to develop this pretty well.
And keep it balanced.
Make this energy source too useful and it'd dominate everything.
Make it too useless and the reader would wonder "why they even bother?".
This is the one fault I see with your idea.
It's especially problematic for an SRW-like verse where many things are meshed together.
But I believe this order of events can also occur without relying on some "super energy source" as plot device.
Actually, your idea pretty much describes the plot of SRW OG in rather broad strokes.
While it had hints of aliens attacks, the plot actually did start with the emerge of the Divine Crusaders which suddenly planned to take over the world.
In short, while with some conditions I detailed above, consider this plot being accepted by me.
So then all 3 of us agree.
On the other hand I'm still wary of beginning the game in a state of "civil war" (as in, humans vs humans).
It'd lead to the players being separated, supporting either group or maybe even neither.
Which complicates things in the beginning.
This "civil war" is a good background and the past allegiance of characters can also lead to interesting conflicts.
But like I said, it'd lead to complications which we might not want in the beginning.
At best we can do a "prologue mission" where everyone is present in the form of a major battle.
Maybe even the one which later decides the war. (If it finishes before the aliens arrive.)
But after that it's the best if we do a bit of time-skip to the present when they're fighting a new alien threat.
That's what I think.
Later there could be strife, betrayals and other twists.
But in the beginning it's the best if it's just black and white.
Humans fighting against the "evil" aliens (who are either really malicious or not, depending on how we develop the plot).