I'm not really up for writing a full FAQ, but I think there are some walkthroughs/information threads on the GameFAQs boards for the game.
About plot (Spoiler Warning!)
The fix-it routes only occur after you've played through the game once. The island of sparkly lights thing is from the first play through, where Rai goes back into hibernation on Kaminejima because his Geass power is going out of control. He uses his Geass to make everyone forget he ever existed around episode... oh, 20 or so of the anime. He's effectively removed from the timeline and one assumes that, were Lost Colors canon, this results in the later events of the anime remaining largely unchanged.
In the Black Knights/Britannian Military scenarios, the massacre never happens because Rai stops Euphie after she's accidentally Geassed by Lelouch, the SAR takes off and becomes a success and you're propelled into a happy shiney AU where things eventually all work out and nobody dies. The Ashford Academy and Blue Moon scenarios end before that point, and I don't know what happens with the JLF route because it's only available in the PSP version which I don't have :P
no subject
About plot (Spoiler Warning!)
The fix-it routes only occur after you've played through the game once. The island of sparkly lights thing is from the first play through, where Rai goes back into hibernation on Kaminejima because his Geass power is going out of control. He uses his Geass to make everyone forget he ever existed around episode... oh, 20 or so of the anime. He's effectively removed from the timeline and one assumes that, were Lost Colors canon, this results in the later events of the anime remaining largely unchanged.
In the Black Knights/Britannian Military scenarios, the massacre never happens because Rai stops Euphie after she's accidentally Geassed by Lelouch, the SAR takes off and becomes a success and you're propelled into a happy shiney AU where things eventually all work out and nobody dies. The Ashford Academy and Blue Moon scenarios end before that point, and I don't know what happens with the JLF route because it's only available in the PSP version which I don't have :P