The Flame in the Flood

You need to shoot with a bow and arrow the following:
Snake
Rabbit
Boar
Wolf
Bear
Crow (These dont die but you need to shoot them anyway)

Notes from ERROR:
This achievements is pretty buggy, as the required days seems to vary from player to player. It unlocked for me on day 49, so don't give up and the achievement will eventually unlock.

Now on to what is allowed and what isn't.

Allowed:

• meat (preferably cooked for best nutrition) - spoils after 4(raw)/6(cooked) days, stacks up to x5

• jerky (raw meat + salt) - the best food resource to have in your inventory, it doesn't spoil and stacks up to x10

• grubs - doesn't spoil and stacks up to x10, pretty rare

• night crawlers - not recommended, it's rare and spoils after 3 days

• spoiled fish - not recommended, it's rare, has a low nutrition and a chance to give you an affliction when consumed

• dandelion tea - used to cure snake bites (unreliable for nutrition purposes only)

• sumac tea - used to cure snake bites (unreliable for nutrition purposes only)

Not allowed:

• cattail - useful resource for crafting various things, do not consume while going for this achievement

• dandelion (the plant itself) - useful for making tea, do not consume it raw while going for this achievement

• sumac (the plant itself) - useful for making tea, do not consume it raw while going for this achievement

• devil's trumpet - useful for later to make tainted bait/meat, since you'll likely carry a lot of meat (to avoid having it spoil), but never consume it

• wild garlic - no point in picking this resource up while going for this achievement

• mulberries - no point in picking this resource up while going for this achievement

• corn - no point in picking this resource up while going for this achievement

• yucca - no point in picking this resource up while going for this achievement

• ash cake (made from x2 corn) - was unable to test if this is allowed the same way the teas are

• cooked yucca - again, unable to test it

In preparation for this achievement, it is recommended that you do a few runs and stack up some resources in your dog's inventory. I usually go for full stacks of raft upgrades (it will make traveling from dock to dock easier), some pieces of clothing (or a stack of hides to craft them later) and of course a full stack of jerky as backup.

This achievement can also be combined with 'Under the Stars' (take the raft shelter upgrade as soon as possible and only rest at the raft from that point onward).

Some tips for surviving 40+ days while going for this achievement:

• take it slow - the further you go down the river, the harder it is to get resources, so stack up on everything early on

• rabbits - kill as many as you can, not just for the meat, but for their pelts as well (which serve for crafting pouches and clothes)

• bears - use them to your advantage, essential for killing wolfs and boars and while doing so, you can also search their caves for various resources

• snakes - I highly recommend avoiding them, while useful for killing small animals (like rabbits), it's unreliable and dangerous (snake bites are lethal if not treated)

• explore - dock to as many places as you can and search every object you can interact with, every resource is precious

• keep trying - don't get discouraged if a good run fails, it will likely happen, such is the nature of rogue-lite games

---------------------------Additonal Notes From Me (Shin)----------
Just unlocked this, it was on Day 45 for me along with Under the Stars.

I wanted to add a few additional tips and observations I made on my run.

• Prepare for this run with one set of Leather Kits, a set of Stitching Kits and Nuts and Bolts on your dog, rush the Rudder and the Shelter for your Raft.

The nuts and bolts to make metal tools and the kits to make a set of bear wear. (I didnt do this but the run would have been easier if I did)

• Prioritize Camp locations for flint and Charcoal (from fires), wastelands are unforgiving without pure water and the flints to make campfires and stone tools.

• For some reason, the bear becomes docile after you sleep, the Shelter on your raft works for this, if you see a Bear, you can go to sleep and when you wake up, the bear will stay asleep.

• Snakes are your best friends. Use a torch to guide them to rabbit holes and let them kill the rabbits. Go to sleep for an hour and they will move away from place.

Even though you might not be able to see the rabbit's corpses, they are there, they dont despawn and you can loot them afterwards.

• Guide snakes in front of a bear's cave, 4 kill the bear, if there is not enough snakes, use traps or arrows (1 trap/arrow = 1 snake)

• You can guide boars/wolves to the bear so they can fight but stay out of sight, once you dont hear any sound of battle, go to sleep so you can sneak past the bear, the boar corpse is usually inside the cave.

• You can also guide wolves to where a boar is, they will fight and stay off your back, useful when there is a pack of wolves in an area you want to loot, Ive waited but they never kill each other.

• Have emergency tea and penicilin so you can heal yourself if you need to eat raw meat or polluted water to survive.

That's it, it isnt that hard but you might get antsy after day 40, stay the course, it will unlock!

Wish you all good luck!

Here is a list of most afflictions for your convenience.

Wet

Hypothermia

Dehydration

Tiny Cuts - Move through bushes/brambles

Ant Stings - Move over Ant Hills

Poison Ivy - Move over Poison Ivy

Laceration - Wolves/Bears

Broken Bones - Boars/Bears

Dysentery/Giarda - Drink Polluted Water

Parasites - Drink Polluter Water / Eat Raw Meat

Staph - Leave Tiny Cuts/Laceration untreated

Food Poisoning - Eat raw Yucca/Devil's Trumpet

And then you have the normal status afflictions which im not 100% if they count like Hungry, Thirsty, Exhausted, etc.

Drunk when consuming Alcohol might also count, not sure, try this last one if you have all of the above but it still hasnt unlock.

Cheers!

Here is a list of all possible deaths for your convenience:

Drowning - The Raft is reduced to zero durability while on the River
Starvation - Scout's Hunger meter stays at zero for a prolonged period
Dehydration - Scout's Thirst meter stays at zero
Hypothermia - Scout's Body Temperature stays at zero
Exhausted - Scout's Sleep meter stays at zero
Wolf Attack - Killed by a Wolf
Gored - Killed by a Boar
Snake Bite - Die from snake poison
Mauled - Killed by a Bear
Sepsis - Untreated cut from tiny cuts or laceration.

Beware, I just attempted this run and even though I did not use any traps or arrows to kill animals, the achievement did not unlock.

I did get skins off animals that fought each other (Bears killing wolves, snakes killing rabbits).. this might invalidated the achievement.

Food wasnt an issue, the cold was. I suppose the game wants you to sleep through cold nights in the last regions without using animal furs.

I'll try again later, its just so darn unfair they dont warn you about these little things.. gaah.. sigh..

Good luck to all.