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