Here is the full list of all 58 Day of the Tentacle Remastered achievements. It takes around 5-6 hours to unlock all of the achievements on Windows.
Sit through the end credits
Defeat Purple Tentacle yesterday
Power Laverne's Chron-o-John
Vacuum up a hamster
Make a skunk
Pick up 45 things that don't belong to you
Acquire a diamond
Get Fred to sign the contract
Wake up Dr. Fred
Ask the IRS agents if they're related
Try to alter the contract with Booboo-B-Gone
Win the human contest
Disqualify Harold
Enter the human contest
Try to wash the dirty car with the brush
Hoagie eats a Hoagie
Squirt five different people with disappearing ink
Return the stamp album to Weird Ed
Try to swap the textbook with the stamp album
Get a tiny sweater
Try to microwave the hamster again after he's thawed out
Deflate Oozo
Power Hoagie's Chron-o-John
Make it rain
Red makes a super battery with only a little help from Hoagie
Make vinegar
Microwave the frozen hamster
Talk to Dead Cousin Ted with all three kids
Clothe Laverne in the costume
Pick up 30 things that don't belong to you
Change the flag
Climb through the chimney with all three kids
Destroy a cherry tree
Create a cherry tree
Try to flush the hamster
Turn off the television
Get a job
Get all six novelty items
Pick up 15 things that don't belong to you
Open the safe
Try to mix the decaf and caffeinated coffees
Play Maniac Mansion
Close a door
Find Fred's basement workshop
Get all other achievements in the game
Play the whole game without skipping a cutscene
Try to sign the contract yourself with the quill pen
Flush 50 objects through time
Laverne tries the chattering teeth on her human during the human show
Talk to Washington, Jefferson, or Hancock while they're outside
Hoagie uses battery with Chron-o-John instead of plug
Reach yesterday without turning the stereo off
Try to mix the red paint and the Booboo-B-Gone
Try to mix the disappearing ink with Booboo-B-Gone
Laverne thinks about eating the cat
Try to put something metal in the microwave
Ring the front desk bell 100 times
Cook the hamster in Maniac Mansion (Don't try this at home, kids!)