Consider everything below to have spoilers. I will be talking about the game like you already know everything about the lore etc. If you'd rather find out things yourself, stop reading the guide. I'd suggest playing the game at least once on your own and then see what you missed, or share your discoveries here.

At some point you will be prompted about what to do with Corpse cards. Bury them, or Cremate them. No matter what you choose, you can still do the other.

Corpse + Soil + Worker + Tools -> Grave (named)

However, after talking with the dev, so far at least there's *nothing* to do with the Grave cards. Grave cards can be deleted like all other cards, by dragging them in the middle-bottom of the screen.

Corpse + Fire -> Remove Corpse Card

You can still cremate them even if you chose "graves" in the prompt.

Note: This to me is silly, I thought graves would at least increase morale, or there would be some way to revive them, that's why I kept everyone. Or maybe many graves would result to some special "graveyard" building, or some special storyline being triggered, but the dev themselves said they added this just because some players want to remember their workers.

So imo, just cremate them.

Explanation:
Your Leader card has a number at the bottom. That's a countdown to death, something like "turns left".

You get a new villager when you raise morale.
You raise morale by eating better food.
The better the food, the more morale it raises.
Each villager has a similar countdown, to their own death.

Secret:
Even from the start, you can add any villager's countdown to your own by sacrificing them.

You place the villager card on the Temporian (even its damaged version).
In the next turn, the villager is transformed to a Corpse card. Their countdown is added to the Temporian.
You place the Leader card on the Temporian.
In the next turn, the countdown stored in the Temporian is added to your Leader's.

In this way, you are practically immortal, as it's really easy to gain villagers later on, even with larger lifespans.

This is weird, because I have no idea what they're used for, if anything.

If you place any item card in the Temporian (not buildings), the Temporian will being emitting a pulse.
In the next turn you will lose that card.
If you place another card, in the next turn you will lose that card and get the previous one.

However, when you now pick up this previous one, the card will have a glitched animation.

This means a new property has been added to that card, that it has travelled in time most likely, but I have found no use for it.

I have tried glitching soil and water, and then making clay out of those two glitched cards, but that clay didn't seem to have any new properties.

I also tried glitching Carving cards, then giving them to the Traveller, but nothing out of the ordinary happened.

So yeah, I don't know if this has any more depth (I hope it does) but I haven't found anything yet.

Can someone add to this?

You gain those early on, they are pink, unlike any other card in the game if I remember correctly, and there's no info on them.

I think I got them by smashing stone with tools (worker + stone + tools), but I now have 5 workers doing that and I only get sand.

In total, I got 3 Carving cards, and I gave two of them to the Traveller, which doesn't seem too interested (only gives like 2 apples for them).

Each Carving card has a different image.

Since these Carvings seem to be rare, they must have some use, but I have no idea what.

EDIT: You get Carving Cards by Leader + stone + tools. You can use them on workers to get an instant boost in their morale.

These are recipes that aren't in the book. I don't remember all of them, but I'll try with some that were really useful. If I write anything that already exists in the book, tell me and I'll remove it.

Please also add to this section with what secret recipe you've discovered!

Fire + Apple + Stick + Worker -> 2x Apple on Stick

2xWorker + House -> Child (takes ~10 turns to grow, 100+ lifespan)

Worker + Child -> Child grows

Villager + Temporian -> Corpse + Countdown transfer

Leader + Temporian -> Countdown transfer to Leader

Card + Temporian -> Glitched previous Card sent to Temporian

Leader + Idea + Research -> The idea is written in the book (apart from secret recipes)

Tower + Worker + Spyglass + Resource -> Gain 1x of that Resource (I know. It sucks)

Bow + Arrow + Forest -> Poultry (maybe an extra card, I don't remember)

Bow + Arrow + Field -> Carcass

(maybe the bow and arrow recipes are in the book? I don't remember)

Note: If you stick to the first 2 recipes, you don't need to worry about anything. I have 2 ovens, 2 chefs, only making "apple on stick", they produce 4 mid-quality food out of just 1 apple. Also, Child cards produced this way have like ~120+ lifespan.

All specializations take a long time normally, a short time with School.
To get School, at some point you will be prompted to choose between Temple (increases morale) and School. In my opinion, get the School, as morale doesn't play a big role later on (and you will have foods to raise it anyway).

To use School, just place a specialized villager and a non-specialized one. In a few turns the non-one will turn to the same specialization as the previous one.

I've only found so far:

- Gatherer: Found when a villager is focused on gathering tasks. For example, gather water from the well, gather apples, gather soil, etc. The gatherer card gathers TWICE what a normal villager does.

- Constructor: Again, found when a villager is only constructing. This will take a lot longer, as you don't need to constantly construct stuff. I'd say try to get this card when you're building Cabins to increase your card limit. The constructor card sometimes makes double what you're building, or other times gets you some bonus resources.

For example, 2xClay + sand + constructor -> 2x bricks (extremely useful)
But 2x bricks + 2x fibers + tools + constructor -> Cabin + 2xPlanks

- Chef: Same as others, gained when focused on cooking. This card gets you twice the food as normal. However, doesn't seem to have an effect on the Press.

4x Apples + Press + Chef -> 2 apple juice (like normal)

Note: I don't know if any others exist, maybe "miner" ? But to be honest, you won't need it.

- On the left of the screen, if you drag your cursor there, there's a space with 6 card slots. You can put there stacks of cards. For example, I put Cabins there, as I have a ton, and you never use them. I also put Calcite and Bones, as they are rarely used.

- You only really need houses to make a village to make a realm for the realm ending. You need at least 1 house to make Child cards. I've never used the village for anything other than healing.

- You can give Idea cards to the Traveller! And he gives mid-food back. So it's good.

- The mid-bottom of the screen has 3 buttons. The right button is "tidy up" which will mess up your configuration. The middle is delete card. But the left button is extremely useful later on. When you click it, it goes through 3 variations. Normal, up arrow, and star. The "star" means the best food you have will be consumed first. The arrow means whatever has less time before it spoils, will be consumed first. Really helpful when you want to boost morale, or making the best use out of the food you have. Some foods are better than other but have a huge lifespan (like Cider) so they will be consumed immediately with the "Star" variation.

- A quarry can be turned to a mine, and a mine back to a quarry! So if you want to get a specific mine, you can go between them until you get the one you want.

- Any farm field will return a Field card when depleted.

- The Greenhouse is really meh. You cannot specialize it, and doesn't give that much.

- The sawmill is meh too, as you can get planks already from worker+forest+tools. With a gatherer, I doubt you will run out of planks, and it's an end-game building, really expensive to build.

- I don't know why bread is so hard to make, but I'd stay away from it if I were you. It requires wheat farm -> 2 wheat in the mill -> flour + water -> dough + oven, and this requires workers the whole time. I'm sure bread is a high-end food, but you can achieve the same stuff with Cider (4x apples + press -> apple juice + shed) for less steps, and shed doesnt require a worker

- Any raw meat you have will become cured in the shed, and will last for a lot of turns.