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