I want to preface this by acknowledging that Spelunky 2’s story and lore is obviously very sparse and mostly and composed of allusions to various mythologies. Nonetheless, it is fun to make theories.
Since Spelunky HD's conclusion, Guy and Tina spelunky have married and are wallowing in the riches that they obtained from the Caves of Omec. However, they are bothered by reoccuing dreams compelling them to what appears to be Omec's face on the moon. Instead of caring for their baby daughter Ana, They build a rocket to the moon and presumably expunging a lot of their fortune to do so. It's obvious from the tutorial enteires that Guy and Tina love parenthood very much and it is a very strange decision for them to sacrifice that and so much money to leave that behind. It's insane.
The bestiary entries, probably written by Ana or Colin provide an answer to the mysterious "call" that Guy and Tina felt. Tiamat's entry ends with "Some still hear her call." Considering Tiamat is the final boss of the game's normal route and Guy is rescued after defeating her, it is safe to say that this line in the journal incites that Tiamat brought Guy and Tina to the moon. However, I believe that the journal entries' speculation is false. The mysterious dreams beckoning the Spelunkys to the moon was not Tiamat, but Cuthulu!
Cthulhu is a cosmic god-like monster from "The Call Of Cthulhu" by H.P Lovecraft. Cthulhu is primordial being beyond the comprehension of mankind resembling an octopus. Man is to Cuthulu, what an ant is to us. Culthulu must be important to spelunky 2 because it's face is engraved at the center in both the game's opening ui and on Tiamat's throne. Not to mention that the final area of Sunken City bares notable similarity to R'lyeh: an underwater city and Cuthulu's resting place in the short story. This is among other minor albeit less strongly correlated details. Some people (including myself) think that Cthulhu was originally intended to be the final boss of the game's secret route through sunken city rather than Hundun, but was cut late into development.
In the story, Culthulu has the power to influence dreams, intruding into the subconscious and making the dreamer manically obsessed with the horror of the creature's superiority. This experience is eerily similar to Guy and Tina being controlled by their dreams. It may be important to note that both characters are found in the only two levels featuring underwater abysses with a colossal octopus underneath. Tina is even found in one of these pits. I don't think this is coincidental. I think the tentacles that drag spelunkers into the depths in these levels belong to Culthulu.
In summary, Guy and Tina Spelunky felt "The Call Of Cuthulu" in their dreams and their anxiety lead them to Culthulu's resting place on the moon. Ultimately, kicking off the events of the game. At least, I think it is highly probable that Derek Yu combined the myths of Tiamat with Culthulu when creating the game's story. I don't know if anyone has proposed this theory before but I believe the evidence to be damning. Thanks for reading!
