Mewgenics Achievement Guide: All 281 Achievements and How to Unlock Them

Mewgenics ships with 281 Steam achievements, a number that Edmund McMillen has described as requiring 500+ hours to fully complete. That figure is not a boast so much as a warning. The achievement list touches nearly every system in the game: zone progression, class mastery, NPC upgrade chains, boss defeats across four difficulty tiers, Side Quest completions, breeding milestones, and a handful of obscure hidden unlocks that exist solely to reward the deeply committed. Many achievements unlock naturally as you play and explore. A large portion, however, require deliberate planning, repeated runs with specific classes, and grinding specific NPCs over many sessions.

This guide covers every major achievement category, what each group requires, which are missable or hidden, and how to approach 100% in a reasonable order. The base game tracks your completion across five broad pillars: chapter clears, NPC progression, house boss defeats, main quests, and class checkmarks, each contributing roughly 20% of the total. An additional 9% comes from specialized bonus challenges like mono-class runs and difficulty-specific completions.

Area Progression Achievements

The most straightforward achievements come from simply clearing zones for the first time. Each new area unlocked in the campaign triggers its own achievement. The main story progression runs: The Alley, The Sewers, The Caves, The Junkyard, The Boneyard, The Desert, The Bunker, The Crater, The Core, The Moon, The Lab, The Ice Age, The Jurassic, The Future, and The End. Clearing each one for the first time pops the corresponding achievement automatically.

Three secret zones require additional steps to unlock and have their own separate achievements: The Throbbing Domain unlocks by completing Guillotina's item quest chain, collecting Throbbing Gristle and the other required quest items from boss kills. The Rift unlocks by completing the item quests for Pyrophina and Zaratana. The Infinite unlocks after finishing all three Act 3 boss item quests. Reaching and clearing each secret zone grants its own achievement. Certain zones also have weather condition unlocks tied to repeated clears: complete the Boneyard three times and Restless Dead and Haunted Night weather becomes available, the Bunker three times for Robot Uprising, and The Moon three times for Alien Invasion.

The Junkyard is worth noting as a branching path: it is only accessible via the hard route through the Alley, not the default path. Players who only take easy routes will never unlock The Junkyard or The Boneyard naturally. Make sure to take the hard path at least once early on.

Class Mastery Achievements

Mewgenics has 14 playable classes: Fighter, Hunter, Mage, Tank, Thief, Cleric, Necromancer, Psychic, Tinkerer, Butcher, Druid, Monk, Jester, and Collarless. Each class has a large set of achievements tied to completing different zones and chapters while using that class. The achievement names follow a naming convention: completing specific zones grants named item achievements (for example, finishing The Jurassic with the Fighter class grants the Battle Axe achievement; with the Butcher it grants Butcher's Cleaver; with the Monk it grants Bo; with the Hunter it grants Bag Of Seeds). Completing The Moon with a class grants a Soul achievement (e.g., Butcher's Soul). Completing all areas with a class grants a final named achievement (e.g., Bag Of Bags for the Thief, Cambion Conception for the Necromancer).

You start the game with access to Fighter, Hunter, Mage, and Tank plus the Collarless option. The remaining classes unlock by clearing specific zones and then speaking to Butch at the hub. Cleric unlocks early after reaching The Sewers. Jester is the hardest to unlock: you need to complete Dr. Beanies' full progression quest chain to access The Rift, then defeat the Chaos boss inside. This means Jester achievements are effectively late-game content. The Collarless class has its own set of achievements including completing The End with a Collarless cat (Ball Of Yarn), which is one of the more prestigious completions in the game.

Reaching specific milestone zones also unlocks passive and ability rewards for all classes. Completing The Caves unlocks starting class ability upgrades. Completing The Boneyard unlocks class passives. Completing The Core unlocks the Path Of the [Class] abilities. Completing The Moon unlocks soul items. These progression unlocks mean that the deeper into the game you go, the more powerful each class run becomes, which matters for tackling hard and crazy difficulty achievements later.

NPC Upgrade Achievements

Several NPCs at your home base unlock achievements through tiered upgrade chains that require feeding them cats over many runs. Each NPC wants a specific type of cat and provides different rewards in return.

Frank accepts retired adult cats that have completed at least one adventure, and rewards you with additional rooms and house expansions, tracked across 4 achievement tiers. You do not need an impressive cat to send Frank: even a cat that just barely cleared the Radical Rat fight counts. Retire your surplus adventure cats to Frank regularly.

Butch is the most critical NPC for practical progression: he controls inventory and storage capacity, and he wants cats that have cleared new zones. His upgrades run 7 tiers. Prioritize sending Butch your zone-clearing veterans early; expanded storage is one of the most impactful improvements you can make, and each tier requires progressively more cats to have reached deeper areas.

Baby Jack (also called Jack) accepts injured cats and uses them to expand his shop inventory, adding rarer and more expensive furniture items at higher tiers. Send cats that were wounded in battle rather than putting them down; they serve a purpose. His upgrade chain runs 4 tiers.

Dr. Beanies accepts cats with mutations, birth defects, disorders, or parasites. After you send him 5 qualifying cats, he begins offering Invention Quests: challenging modified runs that, when completed, convert a difficult side-quest item into a standard usable item. His quest rewards include some of the most powerful permanent tools in the game, and completing his full progression chain is required to unlock The Rift secret zone. His achievements are tied to completing individual Invention Quests, of which there are 21 named side-quest items in the game (Air Horn, Chaos Device, Bubble Boy, Angry Face, Loner, etc.).

Tracy wants large cumulative totals of cats with no special requirements. She provides food storage, collar slots, and idol unlocks across 10+ reward tiers, with milestones at 11, 51, and 91 cumulative cats sent. Tracy's chain is one of the biggest pure grinds: hitting 91 total cats takes many dozens of runs. Tink wants kittens and provides breeding modifiers including inbreeding and aggression toggles across 7 tiers. The Mystery Man accepts dead cats in exchange for organ-harvesting upgrades across 7 tiers.

Boss Defeat Achievements

Mewgenics has nine main house bosses and three secret bosses, each of which must be defeated on Normal, Hard, Crazy, and Impossible difficulties for a full achievement sweep. That is 48 boss-specific achievements before accounting for special conditions. Impossible difficulty is unlocked by completing Chapter 4 content across the secret zones. Each difficulty unlocks after clearing the previous one, so this is a long progression gate.

Guillotina is the first major house boss and has a multi-fight structure across three increasingly difficult encounters. Her fight chain also gates access to The Throbbing Domain secret zone: you need to collect three specific quest items from boss kills (including Throbbing Gristle) to unlock it. Defeating Guillotina on higher difficulties is where the achievement Cap And Bells appears, specifically requiring you to beat the Throbbing King variant using the Jester class. This is a notable intersection of boss and class requirements that catches players off guard.

Pyrophina and Zaratana are the two secret zone bosses accessed through The Rift. Defeating them on multiple difficulties, completing their item quests, and unlocking the Black Shard (Zaratana defeat achievement) are among the harder boss milestones. The Creator is the final boss and has a unique achievement tied to killing it with a Nuke, which requires completing all house boss item quests first. This is arguably one of the longest single-achievement unlock chains in the game.

Side Quest and Invention Quest Achievements

Each of the 21 Side Quest items has a dedicated achievement tied to completing the run while carrying it. Side Quest items are obtained from Dr. Beanies at a rate of one per 5 qualifying cats sent to him. You can hold up to 5 at a time, and the quests must be completed in Chapter 3 or Chapter 4. If the cat carrying the item dies, the item is lost and you must earn it again.

The Side Quest items range from merely punishing to run-ending. A few highlights: the Stopwatch puts every action on a 5-second timer, forcing real-time decision making. The Loner kills all non-boss allies at the start of the run, forcing a solo completion. The Princess Hat limits your cats to only the Walk action. The Air Horn causes all enemies to act before you in the first round. The Angry Face transforms the wearer into an enemy. These are not joke items; they require specifically building your team and strategy around their restrictions. Completing each grants both the named achievement and a powerful upgraded version of the item.

The Persuasion Device is guaranteed to be your first Side Quest item from Dr. Beanies, so that achievement is effectively automatic once you build up a sufficient cat donation pipeline. The Chaos Device and Storage Locker are among the more forgiving quests to complete; the Loner, Princess Hat, and Stopwatch are the most brutal.

Difficulty and Special Challenge Achievements

The difficulty system in Mewgenics runs Normal, Hard, Crazy, and Impossible, unlocking sequentially. Hard difficulty and above adds Elite Buffs to bosses, making encounters significantly more dangerous. Clearing Chapter 4 content (including The Throbbing Domain, The Rift, and The Infinite) on Normal unlocks Hard, then subsequent clears escalate the difficulty options further.

Impossible difficulty is where the Steven achievement chain lives: defeating each individual boss on Impossible is tracked separately and represents the peak challenge of each encounter. The Steven events (triggered by specific conditions mid-run) eventually culminate in a named NPC who becomes a significant narrative and mechanical element of the late-game story. Tracking Steven's appearances and completing his related event chain has its own achievement progression.

Special challenge achievements include completing a full run using only Collarless cats (the Copy Cat run), completing The End with a Collarless cat (Ball Of Yarn), and The Box challenge: beating all chapters with every class on difficulties ranging from Normal through Impossible. The Box is the longest single challenge structure in the game and makes up a large portion of the bonus 9% completion.

Hidden and Missable Achievements

A meaningful number of the 281 achievements are hidden from the achievement list until you trigger them. These tend to fall into two camps: story-based reveals that unlock when you encounter specific lore events for the first time (such as first contact with Steven, certain NPC narrative beats, or triggering unique weather events), and obscure mechanical triggers that require very specific conditions like killing an enemy with a particular ability or status combination.

The achievements most likely to be missed through normal play are those tied to branching paths. The Junkyard and Boneyard zones are behind the hard path in the Alley, which players can skip entirely. Any class achievements tied to clearing those zones will not trigger if you always take the easy route. Similarly, the three secret zones require active quest tracking: if you are not deliberately sending cats to Dr. Beanies and collecting boss quest items, you can progress far into the game without ever unlocking The Throbbing Domain, The Rift, or The Infinite.

Side Quest items are technically missable per-run: if the cat carrying the item dies, you lose the item and must earn it again from Dr. Beanies. This is not a permanent miss, but it is a meaningful setback. Some players recommend dedicating a tank-class cat specifically as your quest item carrier so it is unlikely to die. The Cap And Bells achievement (defeat Throbbing King as Jester class) requires both unlocking the Jester class first and having access to the Throbbing Domain, two prerequisites that can block it for a very long time.

Unlock Chain: Cosmetics and Bonus Content

A substantial block of achievements is tied to unlocking cosmetic items: head and ear cosmetics from defeating the Throbbing King, face cosmetics from defeating Chaos!, and neck and body cosmetics from defeating The Creator. There are also Copycat cosmetics available for completing each final boss fight using only Collarless cats. These cosmetic unlocks are mechanically inert but represent real achievement milestones.

Weapon and equipment achievements unlock from class completions: each class earns a named weapon from completing The Jurassic, and named equipment items from completing The End. Radio songs unlock after 3 completions of each chapter's theme area (6 completions for Chapter 1 content). These are largely passive unlocks that accumulate as you grind class runs.

Tips for Efficient 100% Completion

Start every run with an NPC feeding goal in mind. The grind to max out all NPC upgrade chains is the longest ongoing task in Mewgenics, and each run produces cats you can route toward specific NPCs. Frank gets your cleared adults, Butch gets your cleared veterans, Baby Jack gets your injured survivors, Dr. Beanies gets your mutated and defective kittens, Tink gets your ordinary kittens, and the Mystery Man gets any dead cats. Never let a cat go to waste.

Unlock all classes before focusing heavily on class-specific achievements. The Jester in particular gates Cap And Bells and all Jester zone completions, and it takes the longest to access. Once you have all 14 classes available, you can systematically work through zone completions per class, treating each run as an opportunity to knock off multiple class milestones at once by taking each zone with a different class collar.

For boss difficulty achievements, do not attempt Impossible before you are comfortable with Hard and Crazy. Each difficulty tier adds Elite Buffs to bosses that can completely change the fight. Study the Elite Buff a boss has before committing to a strategy; a Depressing-buffed boss will drain your cats' stats throughout the entire fight, while a Twin-buffed boss splits into two copies at the start. These require fundamentally different approaches.

For Side Quest achievements, prioritize easier quests first to build practice with modified runs before attempting the hardest (Loner, Princess Hat, Stopwatch). Always use a durable cat as your quest item carrier. If you lose the item, do not panic: send Dr. Beanies more qualifying cats on subsequent runs to earn a new Side Quest item and try again. The quest grind will eventually loop back around.

The 500-hour estimate for 100% is real. Mewgenics is designed as a generational grind where breeding better cats, unlocking upgrades, and expanding your toolkit slowly over dozens of runs is the intended loop. Treat each run as progress on multiple simultaneous goals rather than a single objective, and the completion checklist will shrink faster than it appears.