Here is the full list of all 32 My Singing Monsters Playground achievements.
Unlock all Achievements
Unlock all Costumes
Unlock all Decorations
Unlock all 25 Games
Get your first Prize
Try on a Costume
Reach 25 in Gauntlet
Play the Gauntlet... and lose
Win a 3 v 1 game as the solo player
Finish 1st in the 10 Game Tournament
Finish 1st in the 15 Game Tournament
Finish 1st in the 20 Game Tournament
Sink a player in your hole in Bank Shot
Reach 150 in Blast Off
Win without taking a hit in Molten Madness
Win with no bumping in Color Bumper
Collect 60 apples in Apple Grapple
Don't get stunned in Dipster Bop
Land 8 hits in Battle Ball by yourself
Win Driftwood on hard
Don't get thumped on hard in Glowbe in the Dark
Win without moving (jumps only) in Hazardous Hurdle
Don't get stunned in Hectic Hexes and win
Finish 2nd in Keep Away
Win without any boosts in Monster Rally
Absorb everyone in Snow Rollers
Land a double hit in Punch a Bunch
Win without taking any hits in Rocket Punch
Get run over in Thumpede in less than 2 seconds
Win Pastry Puck in Overtime
Capture all players in less than 10 seconds in Tilt a Slime
Score 7 bounces in Bouncin Around