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