Over the course of history, many gods have risen, and so too many have fallen.
Forgotten gods are those gods who have been left behind by the world. Their followers were destroyed by plague or war, or even the God was laid low by one of their rivals.
But you cannot truly kill an immortal without power over them, and for that a most dangerous knowledge is needed: the true mortal name of a god.
Godsnames are hard to acquire, as the ascendency to godhead removes such knowledge from the minds of other mortals. Gods then go about removing any other written record of their true name.
Without a godsname, the immortals of the Ascended Host will find a way to return to existence, and often this is as Forgotten Gods.
When prayers are lacking answers and when all else fails, the truly desperate turn to any and all Forgotten who might aid them.
There is a large garden in the Temple Ward of Queenstown, where once stood the first temple of the city. Broken altars abound here, covered in weeds and overgrowth, and the occasional remains of any desperate offerings.
Sometimes, even a small offering is enough. Sometimes only small miracles are needed. Sometimes, the old gods come back.