The "Big Twist" is that the Bugsnax are actually parasites. They aren't individual creatures that make up an ecosystem, they are one almost hive-like entity. Any Bugsnak can be any other bugsnak and their single minded goal is to be consumed so they can overtake their hosts entirely. They are insidious and patient and addictive. They make you want to eat them.
Lizbert (The character from the trailer) discovered Bugsnax on Snaktooth Island and got a group of people together to make an expedition. Among them are:
Lizbert's girlfriend and doctor, Eggabell
Affable and clumsy Filbo, Appointed Mayor of Snaxburg (the town built on Snaktooth Island) by Lizbert
Scientist Floofty (the NB character for those wanting to know)
Archeologist Triffany and her Farmer husband Wambus
Caring Gramble who thinks of Bugsnax as friends, not food.
Pop Star/One Hit Wonder Wiggle
Gossip Beffica
Conspiracy-Theorist Snorpy and his rad, fitness obsessed boyfriend Chandlo
Sketchy Con Artist/Used Anything Salesman Cromdo
Guru and Reviler of Bugsnax Shelda
Lizbert, in trying to save Eggabell falls into a chasm deep in the underground of Snaktooth Island and finds herself in The Undersnax. The core of the island that shows that it's all Bugsnax, all the way down. When she fell into the chasm, the Bugsnax force themselves down her throat until she is 100% Bugsnak, but in incorporating her she is able to assert her will and somewhat control them rather than losing herself. This however, causes the Bugsnax to retaliate, and the struggle between her control and theirs results in the island beginning to shake apart, causing all manner of natural disasters. Most notably, earthquakes.
With Lizbert and Eggabell gone and unable to catch Bugsnax for the town, and earthquakes starting to scare the residents of Snaxburg, on top of the numerous ideological and personal disagreements among the residents, they all slowly leave town to find their own ways around the island.
--------- This is where the game starts. This is just a main story recap section so feel free to skip if you don't want to read it------
A few weeks later You show up. The Journalist Lizbert invited to share the the discoveries of Bugsnax with the world (before she discovered the truth and was assimilated) There, you see a helpless Filbo exhausted from hunger and collapsed on the ground. He asks you to catch some Bugsnax for him, which you do. He marvels at your capabilities and invites you to town. On the way back, you meet Wambus trying to start his own farm by planting Bugsnax but is not having any luck. He has been able to replant the various Sauce Plants that lay around island though (such as Ketchup, Chocolate, Ranch etc) so has been surviving from that. You show you can catch Bugsnax and he agrees to go back to town to try farming again.
Once there, You conduct an interview with Filbo to try to learn what happened to Lizbert and the other Grumpuses. He then asks you to go to the other Grumpuses, figure out what they want so they'll come back to town and maybe you can figure out what happened to Liz. This is where the game really starts. You start bringing the Grumpuses back.
Beffica (who you meet on the way back to town) is totes bored of the town, makes you her new bestie and if you want her to return she wants GOSSIP. You have to stalk into Wambus' home in the middle of the night and catch him talking to a cactus facsimile of his wife to convince Beffica to return.
You head to the beach and find Floofty, who gives you an item that lets you choose where Bugsnax appear on people's bodies when you feed them, they asks you to turn their leg into a Strabby, then disappears to continue their research.
You then find Gramble, who before owned a barn full of Bugsnax that he wouldn't let anyone eat (until everyone left town and started raiding his barn) doesn't trust the town not to eat all his friends again, especially Wambus who was apparently a core part of doing so. But you help bring some of his lost friends back to him and he agrees to return.
Once these three have returned, Filbo hosts a party to celebrate, but Wambus and Gramble have a big fight over whether Bugsnax are pets or food and whether they can be planted or bred, and especially over what Wambus did to all of Grambles friends once Lizbert disappeared. This ends with them both storming off and Beffica living for this drama.
----Part Two---
Wiggle came to Snaktooth seeking a muse to prove she wasn't a one hit wonder. She's obsessed with Bugsnax and believes that by eating the right bugsnak and transforming her body she will trigger some spark of inspiration. Once you collect the snax she asks for she agrees to return.
Triffany is in some old ruins, studying the ancient grumpuses that lived on the island many years ago. She notices that their skeletons had some bones in their stomachs, but also notes that Bugsnax don't have bones (in fact, if you cut or cook them they turn to mush). She's too caught up in her research to head back to town. You help her discover some blocked caverns that suggest that the old Grumpuses used to bury their dead in dedicated chambers. In order to learn more, and also to reunite with her husband Wambus once you tell her he's back in town, she agrees to return also.
After these two return Filbo hosts a gather round the campfire where the grumpuses tell stories to each other. Rumours of cannibal grumpuses. Beffica even saw Floofty eating a leg. A loud noise is heard, Filbo heads off to the bathroom. You go to check in on him and hear a loud roar coming from the bathroom... but before the door opens you hear Filbo behind you! He says he just needed some air... so what was the noise?! You then hear another crash coming from one of the buildings but discover Chandlo who was just getting some supplies for him and Snorpy up in the mountains.
----Part Three----
The next day, you head to the mountains and find Chandlo and Snorpy living happily together. Chandlo would like to return but he won't leave Snorpy alone, and Snorpy is terrified of the Grumpinati spying on his every action. He won't even trust you until you help Chandlo find some of his basketballs, and Chandlo asks you to turn his limbs into Bugsnax that are especially good at climbing so that he can exceed his limits. Once you've helped him out, Snorpy trusts you enough to help him out. He wants certain body parts changed to Bugsnax to avoid the Grumpinati's spying e.g changing his teeth to Kwookies so that the fillings no longer exist to send them messages. Once you've done this, they both return to town.
You then head back to the ruins and find Cromdo (you can talk to him earlier but you can't help him until now) He thinks Bugsnax are his ticket for a get rich quick scheme and asks you to catch some for him, which you do and he returns.
After these three have returned, Filbo suggests you get an early night and rest. While asleep, you hear Beffica scream in the middle of the night and everyone wakes up. You find her and Gramble at the town entrance where they claim they saw a monster. The town sign has "No More Bugsnax" carved into it, and there are mysterious footprints that change between Grumpus footprints and Bugsnak footprints. The various residents start to voice their concerns and regrets for returning to town.
----Intermission----
During this, you have conducted interviews with the various Grumpuses and they have given you keys and objects that hint towards the fates of Lizbert and Eggabell. Through some video diaries you come to discover that Eggabell was deeply insecure and full of self doubt. Lizbert was a carer and provided her with Bugsnax but this made Eggabell feel worse as she felt that she was nothing but a burden on Lizbert. She resolved to become stronger on her own by training with Chandlo, and resolved to be able to catch her own Bugsnax without Lizbert's help. Lizbert worry that she is eating too many Bugsnax and is further concerned by the experiments that she and Floofty are undergoing, but Eggabell rebukes her, claiming that Lizbert only says these things because she's not the sole provider anymore.
----Part Four----
You head down past the beach to the Boiling Bay where you find Floofty, whose leg you transformed is now a peg leg. They have a theory that Bugsnax can be used to reproduce living matter. You feed them a Bugsnak and transform their leg which now returns (as a bugsnak). They marvel at the medical uses for Bugsnax and upgrades the device they gave you so now you can turn any Bugsnak transformed body part into any bugsnak that the grumpus has ever eaten. So, any of Floofty's body parts that have been transformed can now become a Strabby, or whatever Bugsnak you fed them to replace their leg. This means that all Bugsnax are similar in some way and can become each other. You help them with some more tasks but they conclude their research must be in town in order to continue.
You head past the ruins to the desert where you find Shelda, meditating and preaching against the VILE TOXINS that are Bugsnax. She asks you to break apart some Bugsnax and do some journey things before she agrees to return to town to further tell the citizens how dangerous bugsnax are.
You head to the mountain peak and find Eggabell, studying the area to try and find Lizbert. She refuses to come back to town and refuses your help as she considers everyone to be in danger and doesn't want to endanger you by having you help, but she does agree to let you help her after you prove your capabiilty. You find a door that requires three Grumpuses to stand on pressure plates and she asks you to get Filbo to help. He agrees and the three of you follow instructions in Lizbert's journal to attempt to open the door, but it doesn't work. You and Filbo return to town.
----Part Five----
Filbo hosts another party, and once you get everyone dancing another earthquake occurs. Everyone starts to freak out again and Eggabell shows up saying she knows how to open the door. You head with her and Filbo through the pressure plate door and both fall into The Undersnax
You and Filbo are separated from Eggabell but you find the Snaxquatch monster and follow it into a chamber where you see Lizbert, fully made of Bugsnak into some weird, spider-like monstrosity. She is barely a torso and head on top of a monster. She explains to you the true nature of the Bugsnax and her role in keeping the island from tearing apart, and how she is the Snaxquatch and has been using it to try and scare the Grumpuses into leaving the island. Lizbert is afraid she's can no longer control the Bugsnax and they're all now doomed. Eggabell shows up and forces herself into the Bugsnak monster creature to help Lizbert control them to give the grumpuses enough time to escape.
You and Filbo are flung to the surface where you find the citizens of Snaxburg fending themselves off from the Bugsnax. Depending on how many side quests you've done, how many Bugsnax you fed them and how well you perform in defending them, the residents may all live or die (except Filbo who always lives) and the survivors escape back to the mainland.
----Ending----
You turn your story of bugsnax in to the chief editor of the newspaper you work for, who informs you that you were fired and declared dead the second you left for Snaktooth. Post-credits there is a short scene where your boss is on a phone call with a mysterious voice, which implies that they know about Bugsnax and that there really is a Grumpinati pulling the strings.
The game ends with the two saying in latin:
"You Are What You Eat"
"All Come From Bugsnax"
