These achievements can all be completed on the same playthrough.

Fore!
Feed Onbu with the Onbu Feeding Trebuchet


Just research, build then use the feeding trebuchet with onbu food.


Petting Zoo
Pet Onbu


After both the onbu doctor and pet onbu options have been researched, you will be able to pet onbu form the onbu doctor building.


Berry Good
Achieve 100% efficiency with a Berry Gatherer


This achievement can take a while but is easy to do. Berries spawn throughout the game and always on the grass, because of this you can control where you want them to spawn if you want to get this achievement faster. I will usually setup a berry system like the following if planning to do a long run of the game so you can have more space for farms(X=Berry Gatherer, O=Berry bush/Berry bush spawn)
XOOOX
XOOOX (can flip this as well to make it a horizontal setup)
XOOOX
3 spaces is generally the best since after 4 spaces, the range off the gatherer drops off quite fast.


Doki Doki Waku Waku
Get Onbu's heartrate to go above 6 bpm


Just make Onbu run for a little and this bpm will steadily increase. The bpm meter is just above the time and day on the top right.


Unfortunate Son
Lose a villager on a scavenging mission


Just keep picking the option that has the most likely chance of losing a villager and you will eventually get this.


Parasite
Produce Black Pudding


After doing the research needed for this, you can make this in the kitchen with onbu blood.


Spa Day
Pet, feed, heal and detox Onbu within one day


Should build 3 onbu doctors, 1 each for pet, heal and detox. When 2 doctors have the herbs ready as well as the trebuchet being ready, wait till the time hits 00:00 then pause the game and use all the required abilities from each building. They all should deploy one after the other with time to spare.


Full Body Shave
Cut down every tree on Onbu’s back
Cut every tree including saplings and mothertrees.


The Wandering City
Reach a population of at least 200 villagers


Here is a list of the following recommendations to help you get this.

• The only productivity stats that actually matter are hungry and poisoned as they can lead to starving and badly poisoned respectively, which can then lead to death. This can usually start a domino effect if not dealt with quickly.
  
• Avoid storms as much as possible with high trust, as there is no repair all option so manually doing it one by one can be tedious.
  
• Try to put as many buildings on the dirt as possible to save room for farms/berry gatherers.
  
• Stone is very hard to come by late game so scavenge every quarry you can, unless you build the deep quarry which loses trust with onbu.
  
• Do not put all the farms in one area and instead spread it out so villagers do not need to travel far to get fed. *note - food stands don't seem to work too well at higher populations no matter how many carriers you set
  
• Use the above point for buildings such as decontaminator and village doctor
  
• Build more water wells than water tanks since they will not always be carried to the water tanks and wells will be full continuously, whereas tanks are mostly empty.
  
• Don't feel like you have to try and get new villagers at every opportunity, take it nice and slow so you know how much food you have without overextending yourself.

The Wandering Metropolis
Reach a population of at least 500 villagers
Follow same advice as previous achievement and should get this achievement in due time.


TOTAL: 10 Achievements

I recommend doing these in 3 separate playthroughs as it can get quite difficulty.

Master Gatherer
Survive until day 100 without building any Farms


Can still build a mycologist and a herbalist. Multiple of the berry gatherers are your best friend here to get a lot of food and new spawns happen often.


Strict Diet
Survive until day 100 while using the Onbu Feeding Trebuchet a maximum of 3 times


Recommend doing this in the same playthrough as the above achievement as these 2 are the easiest in my opinion. The best way to get this, is to first get the main research needed for running through deserts then focusing on getting the food liquefier and feeding pump since this does not go towards the achievement. Will only need to use the food trebuchet once, maybe twice while waiting for the research and building.


Dry Spell
Survive until day 100 without building any Air Wells


This is actually a little harder than you might first think. This basically limits to only getting water from the desert biome. Make sure to use plenty of cactus farms and send scavengers to the oasis whenever possible. Use water tanks to stockpile as much as you can and once again use berries for food. You will need the water for herbs and mushrooms so try not to use it on other farms that will require water.


Agricultural Revolution
Survive until day 100 without harvesting any Berries


Honestly this achievement is a bit annoying, I have done multiple playthroughs so I can confirm that this means even clicking the sickle to get rid of the berry bush will not work. Placing buildings on top of the bushes also will just harvest the bush before the building is placed so that does not work either. This also includes farms when adding plots, make sure not to overlap it with any position the berry bush is in.

Only way I can suggest doing this is having a setup in mind really early game and using a cheap building, such as a hut, as a placeholder so that berries do not grow in those locations. Build most of your buildings in the dirt sections and only place the farms and herbalist on the grass since they are the only buildings that need to be in those spots.


TOTAL: 4 Achievements

The hidden achievements all involve building the monument that will unlock when finding the dead onbu. Only 1 monument will unlock for each playthrough. I recommend making a save at day 50-75ish, and strive to get each monument from that save.

Monumental
Build the Survival Monument


Probably the easiest monument to get, you will most likely get this monument on your first playthrough. You get it by not fulfilling the requirements needed for the other 2 monuments described below.


Our Friend and Protector
Build the Onbu Monument


To get this monument I recommend the following:

• Get high trust with Onbu, the more Onbu wags their tail the more they trust you. This includes feeding, curing and giving antidotes to Onbu whenever you can.
  
• 100% productivity or lower.
  
• No damaged buildings

The Light of Human Intellect
Build the Villager Monument


To get this monument I recommend the following:

• Have neutral to low trust with Onbu, can harvest spikes and use buildings that lower trust (bile and blood harvestors must be used at least once). I do not recommend getting to low trust, instead keep it at neutral, this way your buildings to not get destroyed by Onbu.
  
• 120% productivity or higher, easier with a lower population.
  
• 2 or more damaged buildings, I would try and get tornados/storms to do this and can use 'Tents' as fodder.
  
• If at any point Onbu wags their tail during the 100 days, the run will not give this monument.

Got information about this from the following video, so all credit to them https://www.youtube.com/watch?v=pbqKyWP2MYw


TOTAL: 3 Achievements

Thank you very much for reading guide. Please rate and favorite