Upgrades and story are locked behind "weeks" (ie. week 1 is new game, week 2 is new game+),
however clearing the first week with all DLC enabled is not easy due to tricky stages in DLC 2 and a rather challenging true final boss.

Specifically, every area boss has additional story cutscenes that unlock in later weeks and you won't be able to get certain upgrade materials until after week 1.

I'm writing this as a new player (using Daisy) who has just cleared the first week after 31 hours of gameplay, after a lot of trial and error, to save you from making the same mistakes that I did on the first week.

This guide will cover hidden mechanics as well as basic mechanics in more detail, followed by a list of useful parts, and then specific information about DLC 2 and after.

This section will cover relevant basic and hidden mechanics.

Upgrading

One of the first base functions you will unlock is the ability to upgrade parts. For example, you can use any 2 body parts from any monster to upgrade another body part. Better body parts used as materials (eg. from mini-bosses or area bosses) give bigger stat boosts.

However, doing so comes with a severe hidden drawback. The cost of repairing the upgraded body part goes up significantly. You may see repair costs higher than 300 coins very quickly, which may seem far more than you can reasonably sustain.

That said, there actually there seems to be a soft cap on how much the repair cost will rise, so holding off on repairs as long as possible seems to be a reasonable method to sustain usage of upgraded parts.

On the other hand, although upgrading parts is decent source of increasing power, it's a small boost in power relative to the massive increase in repair costs. If you do decide to upgrade parts, I would say to only upgrade the body part to save yourself coin. In fact, I didn't use any upgraded parts on my first clear and mainly used a different source upgrading stats.

Which brings us to...

Attire

From attire materials you can create attire (ie. equipment that you can put on or remove from body parts), and from monster parts you can create genes (ie. balls containing stats). You attach genes to attire and then equip those finished attire to your body parts to gain those stats.

This can easily be your main source of damage increases on the first week.

For example, the body piece on my build at the end of the first week:
Notice that I am gaining 41-60 attack just from attire on the body parts. I have similar if slightly weaker attire stats on the head as well, while I have +12 defense from the single tail on the legs.

The body part has high attack stats built in without any upgrades due to it's blue rarity.

So how do we get good stats on genes?

Obtaining good genes

For crafting genes, basically parts from normal monsters are worthless. Those can be trashed for resources. What you want to keep are parts from mini bosses (ie. stage 2 of each area) and area boss parts (ie. stage 3).

Combining multiple mini boss parts has a chance to give you an attack boosting gene up to level 3, what will be produced exactly varies. You may get a defense gene instead or something else useless (like the frantic gene). I suspect that combining 3 body parts is what gives attack, but I don't really know.

Combining area boss parts can give you better genes, but on the first week it will mostly give frantic 3 (attack speed 3%), which is awful. I suspect that better genes may be locked behind weeks, since I tried some of the exact recipes from the gene guide that were supposed to give elemental damage and they all just gave me frantic 3. Anyhow, I was still able to eventually get some better attack boosting genes from doing this.

Once again, I don't know how to determine what will be produced, though I suspect that body parts are important and maybe even the part that is placed in the yellow box may play a key role. (more investigation needed)

Repairing

Pretty quickly you will unlock a table to repair parts on. This means you can keep using your favourite parts forever as long as you have the coin. See the "upgrading" section above for details on the relationship of upgrade level vs repair cost.

Hidden rooms

Rooms that have a star on the minimap have a hidden room. To find the hidden room, you need to step on some arrows that are on the ground until the hidden room entrance appers.

In this section I will list useful parts I found in each area. This is not a comprehensive list since there are many parts that I never found, and a few that I didn't get to try due one of the spikeshell body's many bugs. So go ahead and try out any parts that you find and judge for yourself whether they are useful, that's the fun part after all.

Area 1

Crawler head


Basic heal, very useful at the start.

Elite crawler head


Basic heal but better.

Spitter body


Weak ranged attack, better than nothing.

Elite spitter body


Probably a better version, but I actually never tried it.

Gluttony feet


A decent early method to dodge, as well as to fly over spikes.

Area 2

Spikeshell body


Possibly the strongest source of ranged single target damage in the game. Also probably the buggiest. Simply equipping this body will make most other bodies cease to function completely until you restart the game. After a while you will find yourself shooting in all 4 directions at once and then the game will crash (it will probably crash anyways though because this game is really buggy). Does melt bosses though. I stopped using it out of principle.

Softie head and body


The head is one of the strongest healing sources in the game when combined with a high attack speed body.

The body does some ranged AOE damage but has a slow attack speed.

Sloth head and body


Sloth's head is a strong if somewhat unreliable source of healing due to the shoddy aim on the turrets.

Sloth's body is an AOE ranged attack with deceptively long range (it goes farther than the animation) that does decent damage with a good fire rate. (though it does less DPS than spikeshell's body) Pretty viable overall, and it's huge and so comes with space for 4 pieces of attire instead of 2.

Area 3

Forest spirit head


A head that let's you dodge an attack every 8 seconds. This is very good, you can avoid a lot of damage and cheese some boss mechanics. Though you will need to rely on food and character passive for healing, and only 70 attire cost is available. This is my preferred head.

Corrupt maneater vinetrap body


An alright ranged attack. I didn't use it much.

Area 4

Hidearther legs


5 second long invincibility with increased movement speed that you cannot attack during with most bodies. The exception is brain maggot body, which is the combo that I personally used. Very good for boss fights.

Wrath head


4 second long invincibility that also heals you, very good. Longer cooldown than Hidearther legs.

DLC 1

I actually only cleared this area once and didn't find anything useful. There probably are useful parts but I didn't find any.

DLC 2

Brain maggot body and legs


Brain maggot body is a passive high attack speed AOE close ranged attack that spins around you. Activate the ability on it to increase your attack speed significantly. The passive attack will continue even if you are flying or underground. This means you can attack enemies while being completely invincible, which is kind of OP. This is what I use.

Brain maggot legs is a worse version of forest spirit head, but it does free up your head slot. If you have both equipped, they will both trigger at the same time.

Cellguard body


Seems to be a decent ranged attack.

Lust legs


A 3 second version of hidearther legs where you can still attack with any body during the invincibility duration.

Pianist legs


Increases your movement speed by 40% at all times. Good if you're confident in manually dodging.

This section will cover surviving the 2 dangerous enemies in the DLC 2 stages and the last 3 bosses before new game+.

DLC 2 stages

Stage 1

There are spider monsters with a jump attack that is hard to dodge. Either attack them from long range or bring a strong source of healing to heal through the damage.

Stage 2

Acid worms will rush you and you will die very fast if you are not prepared. Their attack spins in a circle and it's possible to dodge at close range, however you are better off using a powerful ranged attack to kill them before they reach you. They will also take a break after attacking for a bit, which will give you a window to safely attack and/or reposition.

DLC 2 Area Boss: Lust

This boss has a few attacks:

- Sketch attack: The boss will fire a wide range homing attack at you. She makes a sound when she is about to use this attack. You can avoid this attack by running away for the entire duration. This is a good attack to use invincibility skills for.

- Close range tentacles: Pretty easy to dodge, this is a good time to attack.

- Change to dream world: Lust tranports you to another area and temporarily get's a new moveset. She will use a tentacle attack that can be easily dodged. If you get close to her she will attempt to melee you away.

Pride

Pretty simple boss fight.

Phase 1: Pride will use easily dodged tentacle attacks. The gate will occasionally shoot a laser, so stay away from the vertical center of the room. The gate will also do a wide ranged bullet hell attack occasionally, this can be avoided entirely by staying in the top right or top left corners of the area. However, rocks will occasionally fall, which are supposed to stop you from staying in one place for too long. That said, I just sit in the top right corner and avoid damage using hidearther legs and forest spirit head.

Phase 2: Rocks stop falling, though the gate will continue it's lasers and bullet hell attacks. Pride will alternate between a long duration double laser, and a single laser that will always hit. The double laser can be avoided by getting away from Pride (or use hidearther legs), while the single laser can be avoided with forest spirit head (or you can heal through it). Since rocks no longer fall, the top right and left corners are good places to be.

Demigod

The rather challenging final boss. The boss will use X shaped laser, followed by + shaped laser, and then use a bullet hell attack. The boss only uses it's own attacks when charged by a certain summoned mob.

The boss will summon many mobs that will force you to move, and has a giant HP pool. The fight can be cheesed by losing enemy aggro and making use of invincibility.

It's advisable to use invincibility to dodge the bullet hell attack.

Hopefully this guide will be helpful for surviving this buggy mess of a game.

Good luck on your runs.