Here's what I'm thinking about today ...
step 1 - Big Bang
step 2 - String Theory
step 3 - Snowball Earth
standing astride
option 1 - Volcano based lifeforms
option 2 - Volcano in the Ocean based lifeforms
option 3 - Comet seeding
option 4 - Mars has one of the above + collision + stuff gets here
option 5 - Aliens / Higher Intellects make one of the above happen
option 6 - Aliens / Higher Intellects make one of the above
appear to be what happened
OK
so, then open up Deities & Demi-Gods
and the steps look to me like:
The three Lawful planes might be Step 1 possible, but limited deities involved
The some of the Chaotic planes, can easily be Step 2, and any of the deities work here
Ice and Cold based Deities can cause Step 3, either before or after the 6 options
option 1 is Hephaestus and similars
option 2 is Hephaestus ~fighting Poseidon
option 3 is complicated, but the Hecatoncheres can hurl really huge things, and Atlas can hurl anything
option 4 is Atlas fighting Ares / Mars straight up, and stuff happens when gods fight
option 5 is any race with an Int of 20, or can summon an Efreet (etc)
option 6 is the trickiest, but a mere CO-build above option 5
and then I go whatever.
Anybody have ideas about Science based accuracy in the game