You are a Lighty. But who or what is a Lighty? Lighties are beings made out of light. Nobody knows where they came from but they've probably been here forever. Some say that the first Lighty gathered so much light that it had to leave the Earth and became the sun. Some say that all the stars are Lighties, watching over the planets and the beings on them.
Humans almost never see Lighties and if they do they do not recognise them. Lighties live in a layer of the time-space continuum between realities. Time passes differently there. Light acts differently there.
In between the stars, in the nothing that is space, in the dark nebulas where no light ever travels and most of all in darkspace abide the dark matter entities. They are the lighties' sworn enemies, determined to destroy all light and anything that springs from it.
Now, one of these entities has made it to Earth during a solar eclipse. It managed to prolong the eclipse and without intervention Earth will remain in darkness forever.
It is your task to stop the impending destruction of all life on Earth.