The version I'm thinking of involves a very complex, expensive, and time-consuming ritual spell that invests a target with divine power (the acquisition and use of which there are also rules for). Since the results provide mechanical models for what divine ascension means, the resulting PC is perfectly playable, if beyond the scope of most campaigns.
Pathfinder's Golarion has a neat ascension path built into a dungeon that three core major gods used to ascend, the Test of the Starstone in Absalom.
Never fully detailed for PC use, but narratively a mythic big deal in the setting..
There have been RPGs which explicitly dealt with ascension to godhood, though they've often been derided. SenZar and The World of Synnibarr, as well-known examples, and before them, Tom Moldvay's Lords of Creation.
Before my brother and I moved back to the East coast in '93, Raven made sure to fit in our immortal, demigod, and god quests, so our Synnibarr characters had a chance to ascend to deity status. That game had an explicit endgame of ascension after level 50, with various stages detailed. But you did have to quest.
These two paragraphs don't have to be in contradiction: if the PCs are "mythic" beings, then it makes sense that they might bring about "mythic" changes to the world. And if mythic change means changing or dethroning or killing deities, then that is a thing that PCs might do.
In my 4e game that I described above, killing Torog meant that imprisoned beings broke free (at least until one of the PCs took on the mantle of god of imprisonment and punishment:
Session report - the party comes close to a split, but not quite). Killing Lolth ends the sundering of the Drow from their surface cousins. Killing Orcus means that souls are no longer diverted from the Shadowfell to a horrible fate of undeath. Etc.
Huh? The 4e PHB has Demi-god as an epic destiny option. Epic tier PCs are gods, or chief servitors/exarchs of the gods, or rivals of the gods.
And the combat rules permit the resolution of combat between the PCs and gods, while the skill challenge rules permit the resolution of other sorts of struggles the PCs might have with divinities or similar sorts of beings.
Makes sense that there is an overlap in the Epic Tier and lower ranks of Divinity.
But Demi-god as an Epic Destiny does not let a PC become, say, Zeus (for example).
I enjoyed 4E (my Level 30 Ranger was part of a Party that slew Orcus). But I don't recall any mechanics that made the character 'feel' like a deity. Powerful and super-heroic and indeed "Epic" yes, but there were no real trappings of Divinity: Worship, Divine Realm, Acts of Creation, etc. As such its like role-playing a king without a kingdom.
Right. 4E gives Demigodhood as an Epic destiny, but when you properly ascend at the end of your Destiny Quest you exceed 30th level and "graduate" from being a playable character.
Unlike in Synnibarr or Lords of Creation, say. I haven't read the latter, but in the former you have deity-level activities, quests, God Points gained based on your number of worshippers, etc.
I have never had the gods in my games need human worship and find the idea quite sill actually. I mean they existing eons before humans so why would they need our worship!
Other than D&D, has is (worship of deities) ever been a thing IRL mythologies or religions? It was not like Greek, Norse, or Celtic gods (the ones I am most familiar with) needed human worship. So where did this idea come from?
PS - I know it has been stated as a thing in some D&D context (dragon mag I believe - maybe others), but does it have any RL origins?
I'm not aware of it having a real life source. I think it comes from fantasy fiction and was popularized in D&D by the cosmology of The Forgotten Realms. I'm trying to remember if the concept was included in Deities & Demigods.
Ah, but they do have physical forms - it's just that those physical forms are either immune or highly resistant to anything mortals can throw at them. And PCs in my games have directly interacted with deities on numerous occasions, in (provided the PCs collectively have more wisdom than a kitten) non-combative situations.
What constitutes a "mortal" here is inherently subjective and relatively arbitrary though.
PCs near the top of the defined level scale in any edition of D&D are on the scale of the most epic heroes of any mythology. Capable of striking down multiples of powerful dragons or demons and other monstrous creatures who would be challenges for deities in most real world mythologies.
AD&D characters at high levels (especially with artifacts) are certainly capable of taking on deities.
5E and 4E (and probably 3E, but I never played Epic levels in 3E) make it a little easier and build the system to accommodate it better. They still generally define in the rules that to actually permanently destroy a deity is a super-epic quest which requires a unique process and special tools or weapons. Similar to destroying an artifact in 1E, but moreso.
For example in the first 1st-30th level 4E campaign a friend of mine ran, the finale involved defeating Orcus and then Vecna. But to kill Vecna we had to quest for the Sword of Kas and the Hand of Vecna, because he could only be permanently destroyed with the Sword, wielded in the Hand.