-The cat can only be sacrificed 9 times and becoming a 3 2 on its final life
-feeding the campfire special cards ( mentioned in cabin secrets )
-The two broken obols in act two can form a obol to give to the bone lord (i have another guide already for this so i there isnt a section in this one )

Act 1:

Some of these are obvious but ill list them all

-The skull can be looted for teeth
-The candle can be extinguished to grab a smoke from the bulb
-The clock at 11:00 gives a ring
-Placing cards according to the painting gives rewards
-The safe code is 273
-Giving the campfire certain cards and allowing them to eat it will kill them for the rest of the run allowing you to upgrade unopposed so far i believe this works for ring worm and the adder and any card with poison ( this gives you 4 upgrades every time )
-A few other secrets are linked to progression so ill leave them to be found however choose the arcane eye

Act 2:

By clicking on the tentacle found in two locations you'll be given the card (any order)

The dock found under The shack at the top right of the map

The bath on the top floor of the wizard tower

Act 2:

At the same dock area you visit to see the tentacle for the kraken card there is also a clover you can pickup to reroll your starting hand

Act 2:

There are two rooms with just hidden lore sections that i know of, one is found within the wizard tower by walking up through the top left hand corner to find a passport on floor 2

The other is found near the cabin past the prospector where you take a photo of the fish, just past the bucket

Act 3:
There are plenty more hidden paths similar to the holo pelts and the mycologists hut that have some hidden files behind them or sometimes just upgrades remember to always hover your mouse over the sides where arrows could be but are not just to check

Act 2:

This can be seen more easily with the monocle from the wizard tower, but if you visit the pelt location at the far left of the shack ( top right ) theres a secret path up from the area where you can visit the woodcarver for some lore

Act 3:

The totem ( or whatever you wanna call it ) thats found to the right of the Goo wizards second locations has an interesting secret.

The first icon is found by setting the clock to 11:00

The second is from spinning the drone found past the first bridge ( click on the right or left side of it ) Then clicking on the camera beneath it to light the wall behind it

The 3rd is found from the shadow cast from the box to the right of the totem

The actual sigils are

flying (wing)
insta kill (Skull)
double hit (twin arrows)

Act 2:

The mushroom hut on the centre right of the map can be entered after two scribes are defeated ( sounds obvious but somehow i missed this on initial playthrough) Inside you'll find the mushroom boys asking for duplicates, it'll just cycle between the same 4 with one from each faction. Each of which can be bought from the Trader by repeatedly buying the bottom left slot.

After a few merges youll get a key for later.

Act 3:

Heading to a similar area on the new map ( go up one from the main shop and continue right till you cant ) at this point there is a hidden arrow on the bottom right you can find by placing the mouse over it. This will take you to outside the hut where using the key can take you to a secret boss.

In the second phase they merge your creatures so be careful whats on the board however you can get some powerful cards if you can understand the mechanics of phase 1

Act 3:

The hollow trader is available by clicking on the lock (this opens the door to your left when you leave the game ) in the lab at the top left side of the map, after that there are 5 hollow pelts to collect, one must be purchased from the store and the rest are found on hidden paths that are only revealed when you hover over the hidden arrow.