I forget which game it is, but the notion is that players are Gods. But, they simply have forgotten all of their power.If it were to happen, it would also be as the conclusion of my campaign. I do not plan on players running gods.
Personally I'm not a fan of the "Gods need worshippers." model of divinity. That's not a god, it's a really powerful leech.
edit: there is an artifact that allows someone to skip all of that and become a greater god. The book is a series of instructions (100's of pages long) that have to be done. So far no player character has gotten past page 2.
I would be interested to hear more about this artifact, and how you "handle" in-game.
It has only been found twice in the 15 years or since it was first hinted at way back in 2e. It is a book and like many magical books one can see it detects as magical but not a lot more can be found out until one starts reading it.
The book wants to be read so when one of the PCs found it but was reluctant to read it as any item they can't identify is considered suspect and with good reason the book pressured him. The player happened to be my roommate at the time so to show the pressure after he had it in his possession after a few weeks I would bug him about it through out the week. I also e-mailed him with "read me" messages. It worked out well and didn't annoy him which was a possibility.
He broke down and read the book. Or the first page. Every page was the first page as the book would not reveal page two until page one was read and followed. Each page worked that way.
I'm not sure what you mean by "handle" in quotes and all.
The player followed the instructions of the first page. But once he say the second page it was too much he had to sacrifice he felt to go on. The book wants the reader to become a god, and does not care what the reader wants. So, it wanted him to do things he didn't want to do so he eventually dropped it down a well.
The second time the book was found went basically the same way. At first the player is excited about this challenge but when they realize what it is going to take they aren't willing to go along with it.

(Dungeons & Dragons)
Rulebook featuring "high magic" options, including a host of new spells.