Experimental Adventure: Prequel to Cataclysm - The Dewr Tribe

This bard's goal is to 'gamify' our gaming. Taking lessons from other media and translating that to the realm of tabletop gaming and to provide concrete paths for both the players and dungeon master and in doing so provide strong roleplaying hooks where the expectations are intuitive to character and player alike.
Destruction is not the end; it is rebirth. You must destroy the perfect white of the canvas to paint your masterpiece.
This adventure paints the ending of the world from the viewpoint of but a single tribe in the world as it shatters. This serves as a beginning blueprint for the other tribes and will exist as a creation myth 1,000 years in the future when the campaign proper beings.
Each tribe survives and escapes the destruction in their own way, before reunint far into the future. What ancient memories does each tribe keep? What has been the progress of technology or magic? Chaos allows a diverse cast of genres to be tumultously smashed together, providing an era of great change as their worlds recombine after ages of being apart.
Let this serve as inspiration for you to write your own creation myth adventure, acting as a prequel to your campaign by giving your players a one-shot to set the tone and allow them to contribute to the myths that come to light in the campaign.
Pre-Generated Characters

Morien (MOR yen) - It whirls and spins, making it useless as a navigation tool, but even as a child just holding this compass rose provided comfort. Your village fishes the shrinking seas, so you know better than most how desperate the situation is. The rocking of the sea bring you knowledge in addition hauls of fish.

dwarf and flaming sword by Dean Spencer

Cleric by Dean Spencer

Rhydwyn (HRID win), cleric. You've always felt yourself pulled in two directions, common wisdom says you can only pick one. But... What if there could be a balance? Your village gathers berries, herbs, and healing roots. Being in tune with the flow of the natural world, even in these unnatural times, grounds you to the present and lets you focus on the here and now.

Gwion (GWEE on), bard. The mines have stopped producing, not a trace of minable ore left. The past decade has been tough on your village and thus your faily's prestige. As the youngest child you feel the lack of surplus as there is never enough left for you. Adapting best as you can, you have become a jack-of-all-trades to give yourself the best chance to find a niche to survive in the the upcoming days.

Halfling reading map by Dean Spencer

barbarian drinking by Dean Spencer

Elidir (el IH dir): barbarian. You have a map of the island but names are no longer important so it merely shows the important landmarks since all the matter in their position to one another. Your village knows how to survive in chaos, the wild boar are dangerous and know the forest well. Unlike fish, your meat grows strong children and provides pelts to keep the elderly warm at night.

Most escellent choice! Now we begin.

Setting

Balefire Volcano by Caeora

Fulfilling the prophecy, the World Serpent began the End. Continents shatter as the very earth crumbles under foot. Soon all will end. Entire chunks of the empire have drifted into the roiling sea, scattering all human accomplishments into the wind. Raging for 100 years, humans have formed tribes on what livable areas yet remain. Hope still lives, for some rite to provide salvation, though all know the crescendo is now near.
Trade and communication is now nonexistent, each remaining tribe believes itself to be the sole survivor. You belong to one such trib, the Dewr. You dwell on a volcanic island and though the first decade of the End was tumultious, it has now calmed to an ever present rumble. The forest provides plenty for survival and the population has been slowly recovering.
It is apparent that the earth is not healing. Recent sailing expeditions show the ocean ends in enormous waterwalls, scars that drink the ocean and draw ever closer. Silent lightning flashes above and the volcano roars loudly. Portents most ill.

Anything formatted like this is to be read to the heroes.

With that we begin play...

Problem

Flashes from the heavens show the God's War. Each night darker than the last as celestial Sparks blink out of existance. Last night one such Spark landed on the island, giving the Elders a plan to resurrect their tribe's ancient Protector.
The Dewr are split across four rival villages, each hoping to position themselves as savior, then ruler, over the whole. The Elders know the rite they must perform and need the power of the Volcanic Ley Line to be diverted to them. Each village's leading family sends a representative to begin the ritual and then go into the volcano to divert the Ley Line.

• If hero sacrifices their family heirloom they receive guidance in the form a hint.
• Hero will "sell" their product and thus the greatness of their family, granting them inspiration if they do well.

One by one, the elders will call upon each hero to bring their sacrifice (whether just their village's product or including their heirloom is a secret to other players) and make an impassioned speech, beseeching the powers of the universe to give them guidance. Each hero will "sell" their tribe's main product, hoping to being greater favor for their tribe.
Campaign Note: This changes the future campaign as it determines which families have a powerful magic item from the time of myth. Or it shows how favorable their Protector looks upon a particular family, this can be determined solely through your judgement of the presented arguments or through a skill check. Or a combination. Or a coin flip. This is not divinely inspired gospel, just one bard's opinions. Do whatever you want.

As the final words are spoken, coughless smoke encompasses all. Slowly it parts, revealing a star map. A booming voice announces:
Stars of the past guide stars of the future.
In epoch 1, Heroic An'Bi was born at the Median Blue. Growing larger he went where there was more of the same. Growing weary of repitition he traveled far to the swirling mists. Then he traveled far towards golden fields though none no where ended.
In epoch 2, a mighty rift caused time to reverse, bit by bit An'Bi's progress was undone. Once he returned to his place of birth he felt disoriented. He felt drawn towards the Dark Side and went there to find answers. Here lies the husk of a dead god, and the key you seek to unlock the river of magic.

Star Map for Riddle by ThirstyBard

The Solution - Tracing the path of An'Bi gives the letter N and W, giving the location of the Fallen God on the island. If the heroes need help, gently guide them to their backstories and allow creative use of skill checks for access for more help.
Here the heroes will find a dead diety whose Spark will be used to unlock and divert the Ley line for the Elders. Failing at this task requires them to search the island bit by bit, leading the volcano to get ever violent during their delay. Note this for the final fight as the volcano will be closer to complete destruction.
After the ceremony is complete they set forth together.

Investigation

Using clues from backstories and the ceremony, the heroes must find the Fallen God. How quickly they find it depends on how well they did in the previous section. It is left in your most worthy hands to abjudicate the situation, weiging in the hero's previous actions as well as your player's dispositions.
I would handle this situation completely through narration, describing their travel through the forest and the longer it takes the closer the volcano looks to destruction with them ending at the site of the Fallen Diety. However, a series of skill checks, character abilities, spells, etc. may also be employed. Heck, you may even have a few forest encounters you've been dying to run. Go for it.
Getting to the Gods' Graveyard they must harvest the Spark of a recently fallen god. Echoes of the power based on domain's of influence which can be used to empower the heroes and used to control the Ley Line.
Finally the heroes find the fallen diety...

Complication

To win a fragment of the deity's Spark, must pass a challenge for each domain. Each spark coalesces into a physical item, embuing the hero with the god's last echo of power.
Hints given from the sacrifice of their Heirloom Item give hints for these tasks. Each hero can pick one item that has been unlocked through the challenge. Unlocked items can be picked any number of times.
Life - The counsciouness opens to you, waves of emotions rush. Doubt. Regret. Rage. What does it mean to be a god? How does one judge the past? Uncertainty lingers, making moving forward difficult. Can you answer these questions to help the deity move on? - Lighting Bolt Quarterstaff (Dex Save, 8d6 damage, half on save, 100x5 ft, 7 charges, regains 1d6+1 daily)
Destruction - 3 Minotaur Skeletons attack! - White Wizard's Staff (1 target, Con Save DC14 or incapcitates, else disadvantage on next attack).
Chaos - 2 Gibbering Mouther attack! Can rage # of turns = proficiency modifier.
Madness - Why are respectable inns like the elysium of the gods? Because no bad spirits are permitted to enter them.
How many fathers has a man? Nine: his father, his godfather, his father-in-law, his two grandfathers, and his fore- (four) fathers.
Why is the polka like bitter beer? There are so many hops in it. - Misty Step Rage Wine (bonus action, teleport 30 to place you can see. once daily, goblet refills each morning).
As the volcano threatens to consume the island, the heroes rush into it to complete their task.

Climax

Rumble in the Volcano

Exhausted yet close to the end. Heat envelops your exhausted body, sulfur fills your lungs, and the cacaphonay of draconic screaming verberates through the tunnel. Ahead lies your goal, the chaotic energy of a dying Ley Line.

This scene has two parts:

1. Wave of mephits - Cinematic fight, more theatre of the mind style. Think zombie apocalyse fiction, large amounts of weak minions but the heroes can cut through large groups of them easily. Have groups of mephits swarm each hero and let them blast away.
2. Boss fight - His main goal is to fully activate the volcano, if he is too much for the heroes have him focus his attacks on the Ley Line. If he is successful the cave collapses and traps the heroes in, but still allows them to complete the Ley Line connection so their tribes will be save.

Volcano Rift by Caeora

The heroes need to use the Spark and activate the Ley Line. At least one hero must get to the Ley Line and spend one full round to unlock it, granting
Responsible for release chaos energy from the volcano, Lord of Red, a legendary flame dragon wyrmling. Use the linked stats adding the following: Legendary Actions:Move without provoking attack of opportunity. Make one attack. Search for hidden enemies. Or develop your own for the system you are running.

If they escape:

Radiating bright energy the Ley Line activate and branches towards the village. Rushing after it you come at the village as the Elders finish the resurrection. A lurch in your stomach and you feel a rising sensation. The island rises and the volcano is thrown off. Apparent to you now, the island is the shell of your Protector. Upon its back you fly away from crumbling Midgard and into the vast darkness beyond.

If they must heroically sacrifice themselves:

The volcano crumbles, walls collapse, and escape is impossible. Here lies your last moments. Life given to save your people. The humming of the Ley Line flows towards the village, giving the elders the energy to resurrect the Protector. As your spirit passes into the next world you see the island rise and throw the volcano off. Apparent to you now, the island is the shell of your Protector. Upon its back it flies away from crumbling Midgard and towards the vast darkness beyond.

There is a third outcome, that of complete failure. Though try to avoid it by allowing creative play. Perhaps one player uses the other players as a boat to ride a wave of lava to the Ley Line and unlocking it before succumbing to the heat themselves. Yeah go crazy. If they're all going to die at least let them write their own death. We could all be so lucky.
Broken off from Midgard the next era begins...

The Great DM Planning Sentence: The tribes want to escape Midgard within the next week and is having difficulty doing it because they lack the magical power to do so.
This is just the first attempt at this style of pre-campaign myth setting so let me know what you think! Also write your own so there will be more tribes to play with when they eventually reunite! How will each develop their societies? What other ways can they escape the destroyed planet?