Guide is WIP, maybe bookmark and come back later if it doesn't have what you need? ¯\_(ツ)_/¯

Ginormosia is mostly an optional map that is basically an open world. Not only are most Strangelings obtained through exploring here, certain late-game resources like Platinum Ore and Starry Log can be obtained more easily. Most importantly, there are exclusive bosses that only appear when you rank up the area.

Treasure Grove is procedurally generated dungeons, where basically any resource can be found inside. But with how large the pool is, odds in getting exactly what you want can be somewhat abyssmal.

Neither is "needed" for completing the Main Story, but finishing the Ginormosia dungeon (giant fort in the middle) makes the Main Story final boss fight less difficult.

As mentioned, you can technically obtain any materials from within the Treasure Grove, but it is heavily RNG-dependent and thus less recommended. This guide covers alternate methods in obtaining certain materials:
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=3507324813

• Fish usually only found in Ginormosia
  
• Materials needed for Time-series recipes
  
• Materials easily obtainable from ranking up Ginormosia areas
  
• Boss Materials that are truly exclusive to Treasure Grove
  
• Recommended Locations for getting Mounts from enemy drops

(will tidy later...)

• As soon as unlocked, you want to grab as many Strangelings as you can, just so you can passively level up affinity
  
  • Crafting Life buddies are most impactful as they contribute to about ~50%/~75% of the total crafting stats, which is often necessary to perfectly make your strongest available recipes
    
  • Gathering Life buddies are somewhat helpful in doing Ginormosia challenge, since you get 200 points if completed fast enough. Also helpful in the final Treasure Grove tier because even Oak Trees can be impossible if they are at lv100
• Your followers behave differently during combat and gathering sessions
  
  • All buddies: Can buff you/debuff the node during gathering
    
  • Combat buddies: Can always attack enemies
    
  • Gatherer buddies: May attack or do nothing, would also gather at applicable spots
    
  • Crafter buddies: May attack or do nothing, would restore SP during gathering
• Every roaming Mimic drops a Treasure Grove sapling when defeated
  
  • The ones in cave are NOT roaming Mimic, and would not drop saplings
    
  • The ones that self-destruct have infinite HP, and only drop sapling if you have hit it once before it explodes. Don't worry about dodging and just keep hitting!
• Ranking up an area to lv3 makes the special "blue challenge" start appearing. They are like the normal "orange challenges" but much rarer, and they are the only source of Legendary ingredients for crafting the Time-series equipment
  
  • Ginormosia is roughly divided into 5 regions, one unique boss type per region
    (See the item guide linked above)
    
  • Their spawn rate is mostly RNG-dependent
    
  • You can refresh events in the entire map by changing the area rank at any tower. You can go to Fangshore Isle and keep changing the rank up and and down until the Legendary Don Woolie appears, for instance
    
  • Which tower you refresh at does not seem to affect what event would happen
• Ranking up an area to lv5 allow certain bosses to appear as well
  
  • See my compendium spreadsheet for full list of what are spawned in each area
    https://docs.google.com/spreadsheets/d/1BrBcKh3peA96u3EIj19QROujZLBC4d3ilW-KWyf7Anw/edit?gid=2141234382#gid=2141234382
• Throughout the land are recipes for the Time-series equipment. Recipe Locations:
  https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=3489607336
  
  • Time-series are okay, but not impactful enough to be worth making IMO
    
  • True Time-series provide the highest stats among all tools, but is super expensive
    
  • Gathering Tools remains viable in the end-game. Thus, the Pickaxe, Axe and Fishing Rod are what I recommend to prioritise crafting, whereas the Hoe provides only minimal benefits considering how uncommon wild veggies are
    
  • Crafting Tools become unnecessary when you can already perfectly craft all recipes
    
  • Weapons are all inferior to weapons with element. I cannot recommend them unless you want the glowy cosmetic effect
    
  • The Shield is... there? Technically the best shield, but like, is the 20 defense worth it?
    
  • The meal is the only use for the Meat, Fish, and Spud, so why not

(a.k.a. The Don, not to be confused with the Legendary Don Woolie)
In Ginormosia, a lot of rare materials can be directly purchased from the Traveling Merchant, albeit in limited stocks and only purchasable with Cashnuts. Some of his merch are available by default, but many require his current area to at higher ranks - Most materials require rank 4 or 5, whereas new recipes become available at rank 5, 6 and 7.

• You can immediately refresh his stock by entering a multiplayer session and entering Ginormosia from there. It does not require a second player to join your session
  
  • This can be used to fix his stocks, if you accidentally broke it by accident while changing your system clock forward (time-traveling)
• Most of his wares are not worth buying, either because they are directly purchasable in past-era or you can farm them relatively easily. I recommend only buying the following:
  
  • Recipes
    
  • Boss materials exclusive to Treasure Groves (see Item Guide)
    
  • Non-boss veggie, which can always be sold without loss or even at a profit
    
  • Golden Apple, which can be annoying to obtain
• See the "Don Stock" page in compendium for what he sells exactly at which location
  https://docs.google.com/spreadsheets/d/1BrBcKh3peA96u3EIj19QROujZLBC4d3ilW-KWyf7Anw/edit?gid=816867404#gid=816867404
  
• There are almost always 2 Traveling Merchants on the map at any time. If you only see one, it might be because the other one is hiding in the day/night, so try resting by a village campfire
  
  • (Day-only) Moltana Wastes, Panther Preserve
    
  • (Night-only) East Dryridge Desert, Haniwa Hamlet
• When raining, which happens very rarely on any real-life day, he would offer a 20% discount on all his wares

To obtain more Cashnuts late-game, I highly recommend having 8 full plots of Shadow Carrots at your Base Camp. Stacking enough "Item Drop Rate+" from equipment (both on you and your followers) is especially helpful, allowing you to almost always get 100% of the seeds back from harvesting. This would make the limited stock of Shadow Carrot Seed from Marco less of an issue.

The primary way to obtain Followers is from collecting Strangelings in Ginormosia, and then convert them back into Followers using Celestia's Gifts, the blue flower that spawns each day at your Base Camp. The converting cost decreases based on Island Rating.
- It goes from 100 to 40 eventually
- See this spreadsheet[docs.google.com] for detailed locations
- See this compendium page[docs.google.com] for Strangelings sorted by availability/Life

• All buddies: Can buff you, and debuff the gathering node during gathering
  
• Combat buddies: Can always attack enemies
  
• Gatherer buddies: May attack or do nothing, would also gather at applicable spots
  
• Crafter buddies: May attack or do nothing, would restore SP during gathering
  Also provided crafting stats when applicable (about +50% and +25%)

I would recommend prioritising finding the crafters first. Not only can they help you pass the threshold needed when you are trying to mine high-lv nodes with only low-lv pickaxe for instance, they are somewhat required to pass threshold for crafting recipes at perfect quality too.

Certain crafters also have proficiency that boost the crafting stats of all 3 crafters, making them especially valuable. They stack in the same way as the skills on your Tool and Skill Board, and a smiling face icon would show up when selecting buddies, if such skill is available.

In the beginning, complete challenges lets you earn points very fast. Assuming you didn't take too long finishing the goal, you would earn 100 points for combat challenge or 200 for gathering challenges, so you basically need to do only around 10 to reach Rank 3.

Once an area reaches Rank 3, blue challenges would start appearing there (except for Moltana Wastes and Scorchrock Mountain). These challenges would give a whopping 1000 points when completed fast, and would still appear even if you rank down the area. The main downside is that you cannot control whether one such challenge would appear, but you can refresh all challenges in Ginormosia by simply ranking down and back up any area. Simply keep refreshing until a blue challenge appears, and complete it if one has appeared on the areas you want to rank up.

After about 6 blue challenges in that area, you should be able to rank up said area to Rank 5, allowing exclusive bosses to spawn. There aren't many reasons to keep ranking up other than unlocking additional recipes from the Traveling Merchant, but you can still keep doing blue challenges if you want.

From Rank 6, doing the usual activities for points becomes more efficient:

• Harvest wild veggies (Viridia Plateau only); or
  
• Keep fighting normal enemies for 60 points each; or
  
• Mine ores/Cut trees inside Shrines, which are low-lv regardless of area ranks
  - Each gives a full 180 points
  - You can restart the current stage without proceeding to next, e.g. for farming Magic Ore
  - This method only available in Viridia Plateau, South Greatgut Plains, and Crickneck Canyon
  https://youtu.be/Uq-n0u17sPU?si=-rWuzI6Pddon5B4t
  - There is a combat shrine in West Greatgut Plains too

Here's a quick summary before I wrote the standalone guide...

• In Ginormosia, defeating roaming mimics gives you a sapling each
  
• At Base Camp, planting a sapling creates a new procedurally generated dungeon
  
  • It gives access to basically any resource, albeit it's completely random. As such, it is usually more reliable and efficient to farm materials somewhere else instead
    
  • You can keep redoing the same room so long as the floor hasn't been cleared (where the game tells you "gate has opened up".) This is particularly helpful when you find a good room, e.g. containing many Shadow Carrots
• Finishing a Treasure Grove would increase the level cap for the next dungeon
  
  • You can plant at different levels, but the enemy variety and drops are largely unaffected
    
  • 1 achievement requires maxing out the level cap, i.e. finish 10+ dungeons
• You can replant if you don't like what the random dungeon has to offer, each time taking a new sapling and the game auto-saves
  
  • Quick reminder that save-scumming is an option, where you either manually backing up your save or using the cross-save feature
• Some materials are exclusively found almost only in Treasure Grove
  
  • These materials are needed for maxing out each crafting life's rank
    
  • You want to look for these bosses when doing a grove, and replant if you don't see one
    
  • See the "Treasure Grove" section in this guide:
    https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=3507324813
• Sometimes there are rare rooms in a Treasure Grove, each with a unique icon
  
  • Treasure Trove: Lots of chests, but most contain only Sack of Gold
    
  • Souped Up Strangeling: Each provides 10% boost (?) to their stat of a specific NPC
    
  • Monster House: A room containing only shadow sonsters - Good for farming Dark Fire and slates after finishing the Main Story
    
  • Aging Altar: Gives additional skill to weapon/tool, but is completely random and not worth going after; Also needed for 2 achievements
• I don't like Treasure Grove
  
  • Would recommend checking the Ginormosia Traveling Merchant instead, this way you can buy all these rare materials without the hassle of running through 10 floors each time

I have put together various other tips & tricks in this separate guide and the Compendium spreadsheet as well. You may find more useful information there, check it out!
Google Sheet[docs.google.com] | HTML View Mode[docs.google.com]
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=3484233912
I have jotted down various Life-related tips, which you can see in this guide:
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=3500367872
Quite a number of recipes are obtainable only from Islanders. See this guide for details:
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=3493902047
This guide contains a quick summary on obtaining all achievements:
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=3505903847
This guide contains a quick reference for various not-easily-obtainable items:
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=3507324813
This guide covers 2 useful exploits that could be helpful in the end-game:
https://steamhost.cn/steamcommunity_com/sharedfiles/filedetails/?id=3510285845