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.
Insert every song into GINO'S JUKEBOX.
Feed the STRAY CAT every day and sunset.
Go to SEAN and KAREN's housewarming party.
Defeat the RECYCLEPATH.
Give FLOWERS to MARI.
Defeat the HOOLIGANS with PEPPER SPRAY.
Battle the "bees".
Take $20.00 from KEL's wardrobe.
Don't high-five KEL.
Defeat the PET ROCK champion.
Complete the grammar worksheet correctly.
Complete the math worksheet correctly.
Get a perfect score delivering PIZZA.
Complete all part-time jobs once.
Quit in the middle of a part-time job.
Reach the other ending.
Get all rewards from the RECYCLING MACHINE.
Take the KEEPER OF THE CASTLE's power.
Read all the tombstones in the... dev room...
Defeat PERFECTHEART.
Complete the FOE FACTS! journal.
Defeat MUTANTHEART.
Beat the BOSS RUSH.
Defeat ROBOHEART.
Defeat every SOMETHING at the bottom of the LOST LIBRARY.
Commission all of ROCOCO's art.
Defeat 100 SQUIZZARDS.
Visit all mirrors.
Defeat UNBREAD TWINS.
Recover at all of MARI's picnics.
Defeat the CHICKEN? at the top of DINO'S DIG.
Defeat 100 BUNNIES.
Commission all of GATOR GUY's statues.
Defeat PLUTO and THE EARTH.
Defeat SPACE EX-HUSBAND.
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.
Get the LOL SWORD.
Trade CLAMS for CLEMS.
Have a ghost party.
Complete ORANGE JOE's quest.
Turn the valve to the right in RAIN TOWN.
Commission ROCOCO.
Watch all movies in SWEETHEART'S "throne room".
Hold 99 TOFU.
Choose the WINTER MOLE.
Choose the FALL MOLE.
Choose the SPRING MOLE.
Defeat THE EARTH.
Defeat ???.
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.
Listen to MR. SCARETHROW's rant.
Throw away something.
Defeat HUMPHREY.
Defeat SLIME GIRLS.
Pet all the creatures in MARINA's sector in HUMPHREY.
Defeat PLUTO (EXPANDED).
Defeat MR. JAWSUM.
Gain BREAD using BREAD SLICE.
Pet a dog.
Defeat SWEETHEART.
Perfectly train the SPROUT MOLE choir.
Kill the first SOUS CHEF.
Ruin Christmas.
Choose the SUMMER MOLE.
Go to sleep after a long day.
High-five KEL.
Lose to KIM and VANCE.
Wake up in the morning.
Make your way and talk to LONE MOLE.
Defeat SPACE EX-BOYFRIEND.
RELEASE ENERGY on your foes.
Defeat DOWNLOAD WINDOW.
Water a plant back to life in BASIL's garden.