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