Here is the full list of all 84 OMORI achievements. It takes around 80-100 hours to unlock all of the achievements on Windows.
Defeat PERFECTHEART.
Unlock all achievements. Thank you for playing OMORI.
Complete the FOE FACTS! journal.
Recover at all of MARI's picnics.
Look through all telescopes.
Visit all mirrors.
Reach the other ending.
Brush your teeth every day.
Defeat SPACE EX-HUSBAND.
Commission all of GATOR GUY's statues.
Defeat MUTANTHEART.
Beat the BOSS RUSH.
Defeat PLUTO and THE EARTH.
Defeat every SOMETHING at the bottom of the LOST LIBRARY.
Let the plastic fish finish its song.
Take the KEEPER OF THE CASTLE's power.
Get the FLOWER CROWN from BASIL.
Complete your TO-DO LIST.
Read all the tombstones in the... dev room...
Defeat ROBOHEART.
Defeat the CHICKEN? at the top of DINO'S DIG.
Commission all of ROCOCO's art.
Defeat 100 SQUIZZARDS.
Defeat UNBREAD TWINS.
Get the LOL SWORD.
Have a ghost party.
Trade CLAMS for CLEMS.
Complete ORANGE JOE's quest.
Commission ROCOCO.
Turn the valve to the right in RAIN TOWN.
Get all rewards from the RECYCLING MACHINE.
Reach the bad ending.
Reach the good ending.
Receive all FLOWERS in the hospital.
Insert every song into GINO'S JUKEBOX.
Go to SEAN and KAREN's housewarming party.
Feed the STRAY CAT every day and sunset.
Give FLOWERS to MARI.
Defeat the RECYCLEPATH.
High-five KEL three times.
Defeat HUMPHREY.
Defeat SLIME GIRLS.
Pet all the creatures in MARINA's sector in HUMPHREY.
Defeat PLUTO (EXPANDED).
Defeat MR. JAWSUM.
Don't high-five KEL.
Defeat the HOOLIGANS with PEPPER SPRAY.
Take $20.00 from KEL's wardrobe.
Battle the "bees".
Defeat SWEETHEART.
Watch all movies in SWEETHEART'S "throne room".
Hold 99 TOFU.
Choose the FALL MOLE.
Choose the SUMMER MOLE.
Choose the SPRING MOLE.
Defeat KITE KID.
Defeat the PET ROCK champion.
Get a perfect score delivering PIZZA.
Quit in the middle of a part-time job.
Lose to KIM and VANCE.
Complete the grammar worksheet correctly.
Complete the math worksheet correctly.
Pet a dog.
Defeat ???.
RELEASE ENERGY on your foes.
Defeat 100 BUNNIES.
Gain BREAD using BREAD SLICE.
Throw away something.
Fly the BUTT CERTIFICATE in CATTAIL FIELD.
Enter code: haveadollariguess at www.omocat-shop.com for $1.00 off.
Perfectly train the SPROUT MOLE choir.
Kill the first SOUS CHEF.
Ruin Christmas.
Choose the WINTER MOLE.
Go to sleep after a long day.
High-five KEL.
Complete all part-time jobs once.
Wake up in the morning.
Defeat THE EARTH.
Defeat SPACE EX-BOYFRIEND.
Make your way and talk to LONE MOLE.
Listen to MR. SCARETHROW's rant.
Defeat DOWNLOAD WINDOW.
Water a plant back to life in BASIL's garden.