Here is the full list of all 222 Who's your Santa!? achievements.
Forget to freeze the bear
Good Game! Happy holidays!
Poisoned
Shoot two plates with bottles in the reactor room
Shoot the plate with a bottle in the reactor room
Double failure in the race! Next time will be easier
Beat the game in hardcore mode, without first passing on Normal
Almost all achievements are collected…almost…and this annoying U
All achievements are collected
Complete the race on Normal without taking any damage
Complete the race on Hardcore without taking any damage
All three races completed on Hardcore without taking any damage
Collect all the gifts
Collect all the gifts and do not spend a single health
Three times a failure in the race! And it couldn't be easier this time...
Man was killed three times
Fail in the first race
Fail in the second race
Collect black X-clouds
Collect white clouds
Fail in the third race
Zen was comprehended…that was painful
Destroy 6 thunderstorm clouds without taking hit
Lose by colliding with vortices only
Lose by colliding with tall buildings
Waste your last hit point on the homestraight
Didn't lose any health, but still forgot to pick something up
Forgot to pick up something
Did you go there for a cup of tea?
Smash all the bottles and don't poison yourself.
Shoot all the plates with bottles in the reactor room
Who even needs these gifts
Crush everything on your way
Wiiiiin!
Samovar-rocket start
Face with the Bear
Calm Keeps You
Thrum the strings three times
Small clicks for the player, one big flight for Kuzma
Nice try, but Kuzma did not take off
Find out what does the tank shoot with
Where does a grenade come from? Maybe they'll show it in the news...
Find the cockroach and make it nuclear mutate
Complete a location with hat and camera in inventory
Pull the bath curtain, if you dare
Balls scattered on the floor - classics
Leave the fireplace closed
I'll be back
Forget to neutralize signal with gag
Touch the fireplace decorations
Smells like...victory
If you shake the refrigerator for long...
That was the weirdest dating sim ever
Find the tool and free Cthulhu
Drop shampoo in the bath
Omnomnom
Go into the bathroom, stay unnoticed
You were noticed in the bathroom
You were noticed in the bedroom
Make confetti from a plate
Light the tree, shoot a bottle in the star
Now you know who's done it... well, almost