Meet Merle, an all-7-stats, 10-positive-mutations cat born in-house!

Intro:

Due to this terrible and horrible thing called "real life" catching up on me, I only finally had the time to breed my own perfect cat just now today. As there is a lacking of understanding of this sort of cat breeding method on reddit and in English community in general it seems, it's time for me to write my first long, comprehensive gaming guide , with the goal of consistently breeding a lineage of all-7-stats, 10-positive-mutations :D.

I do not claim originality for everything in this post. A lot of knowledge and inspirations came from multiple other players who spent time researching breeding mechanics in Mewgenics, with special thanks to |九号玩家| on Xiaoheihe.

Before We Start:

You need to get the rooms and furniture ready. The breeding basics had been covered pretty thoroughly by many existing guides, so I will go over this part quickly. Due to the difficulty of acquiring furniture, it's recommended to at least complete chapter 1 before you even start worrying about breeding. Just use the strays for chapter 1, you will be fine. On topic of house invader boss: if you are not comfortable fighting them, you can always just send out a veteran stray fresh out of the alley for them, though I prefer to work on breeding when no invasion is possible (by finishing the last invader & not completing the next map route) so I have peace of mind.

Notes on furniture:

• Stack as many Comfort and Stimulation as possible in the main "breeding room" - aim for at least 15 in each, up to 30 if possible. When nearing the cap, prioritize Stimulation over Comfort.
  
• I know money is hard to come by, but try to grab those +Mutation and +Health furniture if possible. Those are rare and will be needed later.
• Pick the hard route whenever possible for furniture boxes. In the second maps (sewer/junkyard), the path will split into two. The treasure chest is an item, while the cardboard box will be a furniture. I've always chosen the furniture once I learned this.

Take the box, take the box

Notes on money:

• Doing quests for Dr. Beanies will give you $200 for each quest. Though for some items, such as the Storage Locker (change passive upgrade to a rare item drop), it's recommended to not complete the quest in the first try to maximize use out of the item. Also, once you unlocked Throbbing Domain, the quest might ask you to bring the item to there, so not progressing the story too fast will keep your quest simpler if you want to focus on breeding first.
• With the quest item Mama Leech on a cat with Russian Shorthair Roulette, when the cat drew the bullet and shot itself for 999, mama leech sucks that 999 back, rending the cat unharmed. So you can farm infinite money with this trick - except it's not infinite at all - it caps at 99 in the run, which you can easily get with a thief. So is just a funny trick to know I guess.

Notes on npcs:

• To be honest most npcs are important for breeding. Besides Tink the obvious option, you also want to donate those 25 veteren cats for at least 3 rooms in the house (more importantly - having 3 rooms will make your attic biiig, for finally stacking those 30 Stimulation. Furniture guy will give furniture (also rare furniture if you donated enough), and the P-smart girl turned out to be extremely important later on as she sells unique statues including one that gives flat +5 Stimulation, one with +5 Mutation, and one that prevents breeding - if you adventure often enough for food, it's recommended to have a room to hoard all the strays until they reach 5 and donate them all to P-smart.

Notes on items and traits:

• If you ever see Uranium Rod and Cancer, grab them! I will expand on those in the mutation section.
• Other useful items to keep: anything that prevents injury (Bulletproof Vest), fix injury to a certain stat that's not Charisma, or things that help your cat kill itself, such as Death's Scythe (conflict with uranium rod), or Crown of Pestilence.
• Same applies to skills. Play Dead pairs nicely with uranium rod, whereas Bare Minimum goes well with Cancer, so keep them whenever you can.
• Tainted Genes, a disorder, functions as Cancer with much less downside. Keep it!

Step 1: Breed Cats With All 7 Stats

There are many guides about this out there, most of them with a heavy focus on how to avoid inbreeding penalty. We do not care about inbreeding penalty, so this step is extremely easy. Just collect strays with at least one 7 stat (might need some amount of Appeal furniture for them to start appearing), breed them together in that high Comfort and Stimulation room until you have a cat with two 7s, and breed those siblings together with a new stray until you have three 7s, and rinse and repeat. Without considering inbreeding, you can breed imperfect cousins (who each have maybe 4-5 sevens in different stats) together, significantly speeding up the process. Cats whose both parents have base 7 in one stat can only ever be born with base 7 in that stat. So once you have a pair of cats with all 7s in all stats, your incest family can only ever have 7s in their blood.

My family tree is a ladder, but it's ok!

As usual, prioritize gender fluid (?) cats, keep an eye on the Bi, and shun the gays. Prioritize horny cats and cats younger than 15, punt the celibates immediately.

https://preview.redd.it/2ev4ze6a6qkg1.png?width=225&format=png&auto=webp&s=3aac92e72fcc60ef32f665a5a0428e0182515ee6

Note that Birth Defects will start to popping up from all the inbreeding by now. Most of them don't matter that much, but you still want to prioritize keeping those with less defects, and trash those kittens with extremely detrimental ones (e.g. One defect gives 2 rounds of confusion at every fight - avoid like plague!)

Step 2: Get Those Mutations!

Now this is the part where my guide becomes new. Remember those two items and one disorder I mentioned earlier? Let's read those stats:

https://preview.redd.it/ak2qceex1qkg1.png?width=773&format=png&auto=webp&s=92163ad8ee2733496775779e53ddbd849b147158

https://preview.redd.it/8rwfaknr1qkg1.png?width=714&format=png&auto=webp&s=d192e771bf84770ee924945d63855f57475242b2

https://preview.redd.it/hhgkhaz55qkg1.png?width=779&format=png&auto=webp&s=cf76308baf7b449819db49d143021e0d7646eff9

Here's the trick: When a kitten is being born, they can maximumly come with 1 mutation (good or bad) in each body part, making it 10 total. So when they inherited 10 mutations from both parents, they cannot have birth defects! (They will, but we'll fix that later)

The goal here then, is to acquire a pair of "parents" cat that have at least 1 positive mutation in each body parts. Gaining a mutation in a body part will over-write the birth defect there.

There are several ways of achieving this, the fastest is with Cancer and Uranium Rod. Just equip those items, go on an adventure, and reap those sweet sweet mutations each fight. I recommend going Graveyard over Cave, as I find it easier to keep my cat's body from being eaten by zombies vs by spiderlings.

For Cancer, having Bare Minimum passive will keep your cat at least useable in later fights. Even when you don't care about their combat performance, do note that Charisma seems to affect breeding success, so you want those numbers positive! If you already have a negative charisma cancer cat, stuck them in the 30 comfort room anyway and pray for love beyond looks... the chance it abysmal, but it's there. It will be fixed next generation.

For Uranium Rod, Bulletproof Vest will prevent injuries from happening, which again, dooms your stats. Using Play Dead will not incur injuries. It's recommended to use Thief as the job, so that the cat moves first in turn, and can safely do a round of damage before it kills its 1hp self. If you foresee the fight lasting longer than 1 turn, you can keep the cat alive for longer, just make sure to kill it with a teammate before end of battle. Necromancer is also a solid choice for dead cat shenanigans, but do be very careful that having Eternal Health passive WILL doom your run, as it conflicts with the uranium rod and does not count the necromancer as dead to trigger the mutation. So yeah I recommend playing thief. Just be very careful to not let the body get destroyed. Go to Graveyard.

Will void Uranium Rod, do not take!

For either items, I highly recommend to equip your mutation cat with a Neverstone. They are not gonna be of much help in the runs anyway, might as well make the other three cats stronger. 3 cats runs are arguably stronger than 4 cat runs anyway. To farm this item easily, go out with 3 cats of your liking plus 1 random sacrificial stray. Kill the stray in battle and destroy its body. Soon after you will get an event for a new lv1 cat to join your team, bringing an Neverstone with it.

Your sacrifice will be appreciated, random stray

The Storage Chest quest item might help in sourcing these items, too bad it's breakable even if you don't finish the quest.

If you truly have no luck in finding either items, go to the Crater and pick the Shimmer weather whenever it's an option, which will yield 3-4 mutations. Ooor, just grind in the high Mutation room if you happen to have a lot of furniture there.

High chance to appear in Crater weather event, but not guaranteed

As cats can get multiple mutations for the same body parts if they get them in an adventure, you might not be able to get a full 10 body-parts mutation cats in the first try.

Minimu, first gen sire of the family

I didn't have a screenshot for the parents of this cat - who both have ~12 mutations but also 2 defects, because they had duplicate mutations that don't cover all the body parts. The next generation inherited 7-8 mutations, so I sent the next generation on another radioactive trip to gain this beauty, who is my original Sire of the perfect cat family. You need two of these (prioritize the ? and the horny!), ideally with mutations you like. My second sire candidate has several "knock back on attack" mutations, which is technically positive but I personally hate, so I had to abandon that one and went on another run.

Step 3: Maintaining Future Generations:

At this step, we have a pair of cats with all 7 in all stats, and positive mutations in every body part. They are ready to breed you a whole cat dynasty!

Except one thing. Their kittens, you will notice, will still be born with a small imperfection: they will consistently have 9 mutations and 1 birth defect:

Merle's sibling 1

Merle, newborn!

Merle's sibling 2

But don't worry, this is easy to fix: to the Mutation Room!

For the Mutation Room, you want to stack high mutation (I only have 7 currently, it's not ideal, but it works), but also keeping the Health positive (a lot of mutation furniture lowers health). If you have the statue from P-Smart that prevents breeding, put them in the room. This does many things: 1. Prevents imperfect 9-1 cats breeding more imperfect cats, and more importantly 2. Prevents relationships from forming, so they don't fight due to conflict love interest, and can develop new love bonds with the intended cat if they get promoted to the breeding room later. Cats with the same love interest will always fight no matter how high the Comfort of the room is, and cats that love each other will breed more.

Merle, evolved!

I'm not sure about the exact mechanics, but it seems to be quite consistent that the first mutation a 9-1 cat get in the mutation room will always replace the Birth Defect. If it's a powerful mutation that you'd like to keep in the family, promote it to the breeding room in the attic, where at this stage you should only have 1 or 2 pair of cats for optimally controlled breeding.

Next Steps:

Actual Perfect Mutations: Keep replacing the breeding pair with better mutations. +2-1 mutations are better than nothing, but they are not the strongest. Some noticeable good ones include a Head Mutation that gives 1 extra attack on the first turn, and a Tail Mutation that let you reroll your level-up skills once every time. I'm sure there are many powerful ones out there.

Fighting Club: If you have spare rooms, you can also set up a room with minimum comfort (as in like, negative comfort) as the fighting club. Toss all the cats that's not good enough to be a breeding pair but good enough to go on adventure in there, and let them fight to death. Each time they win a fight, they will gain 1 stat (2 if you have the P Smart fighting statue). I'm personally meh about this strat as you risk injury and death, but you can get some seriously powerful cats out of there. It's good when you have more cat than knowing what to do with.

Passive and skills: I also read somewhere that Stimulation actually only affects stat inheritance very little (0.5% chance for 1 point), but greatly affects skill and passive inheritance rate. So get some good skills from adventure, and breed those into your kittens. I will not go into the details here (like that's a whole book), but there are many broken combos out there. Might make the game boring if you start every game with the same broken combo tho, so save for the most extreme difficulty.

Final Words:

Thank you for reading the guide, and let me know if there's any questions or anything I did not cover and can improve on in this guide.

Special thanks to my most perfect cat in possession. No amount of hardcore min-maxing can surpass something that's born perfect.

Meet Bane, my co-author!