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.
Reach the bad ending.
Insert every song into GINO'S JUKEBOX.
Feed the STRAY CAT every day and sunset.
Defeat the RECYCLEPATH.
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.
Quit in the middle of a part-time job.
Complete the math worksheet correctly.
Complete the grammar worksheet correctly.
Reach the other ending.
Take the KEEPER OF THE CASTLE's power.
Commission all of GATOR GUY's statues.
Defeat PERFECTHEART.
Commission all of ROCOCO's art.
Complete the FOE FACTS! journal.
Beat the BOSS RUSH.
Defeat ROBOHEART.
Defeat MUTANTHEART.
Recover at all of MARI's picnics.
Read all the tombstones in the... dev room...
Visit all mirrors.
Defeat PLUTO and THE EARTH.
Defeat every SOMETHING at the bottom of the LOST LIBRARY.
Defeat 100 SQUIZZARDS.
Defeat SPACE EX-HUSBAND.
Look through all telescopes.
Let the plastic fish finish its song.
Get all rewards from the RECYCLING MACHINE.
Get the FLOWER CROWN from BASIL.
Complete your TO-DO LIST.
Brush your teeth every day.
Pet all the creatures in MARINA's sector in HUMPHREY.
Defeat 100 BUNNIES.
Defeat UNBREAD TWINS.
Throw away something.
Choose the SUMMER MOLE.
Choose the SPRING MOLE.
Choose the FALL MOLE.
Defeat THE EARTH.
Enter code: haveadollariguess at www.omocat-shop.com for $1.00 off.
Reach the good ending.
Go to SEAN and KAREN's housewarming party.
Give FLOWERS to MARI.
High-five KEL three times.
Defeat the CHICKEN? at the top of DINO'S DIG.
Defeat HUMPHREY.
Defeat SLIME GIRLS.
Have a ghost party.
Trade CLAMS for CLEMS.
Commission ROCOCO.
Get the LOL SWORD.
Defeat PLUTO (EXPANDED).
Defeat MR. JAWSUM.
Get a perfect score delivering PIZZA.
Defeat SWEETHEART.
Hold 99 TOFU.
Watch all movies in SWEETHEART'S "throne room".
Kill the first SOUS CHEF.
Perfectly train the SPROUT MOLE choir.
Ruin Christmas.
Choose the WINTER MOLE.
Complete ORANGE JOE's quest.
Pet a dog.
Defeat KITE KID.
RELEASE ENERGY on your foes.
Turn the valve to the right in RAIN TOWN.
Go to sleep after a long day.
High-five KEL.
Complete all part-time jobs once.
Wake up in the morning.
Defeat SPACE EX-BOYFRIEND.
Listen to MR. SCARETHROW's rant.
Defeat DOWNLOAD WINDOW.
Gain BREAD using BREAD SLICE.
Make your way and talk to LONE MOLE.
Defeat ???.
Fly the BUTT CERTIFICATE in CATTAIL FIELD.
Water a plant back to life in BASIL's garden.