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