Welcome to Primal Gods!
The players take the part of celestial beings – angels and demons – as they struggle for control of humanity and themselves. The celestials, powerful though they may be, are merely pawns in a much larger game being played by their Superiors, the Archangels and Demon Princes. The game is expansive, drawing on a number of timelines.
Here is the information from the Campaign Planning Form from the GURPS Basic Set, which I will fill in gradually:
Campaign Planning Form