Here is the full list of all 21 Ricochet achievements.
Open Ricochet For The First Time
Enter The Station
Enter The Forest
Enter The Sky
Enter Hell
Enter The Mines
Enter Space
Heal An Opponent With A Bullet
Hurt Another Player
Damage yourself
Leave the museum
Play a match for more than 5 minutes
Deal 1000 Damage
Deal 2500 Damage
Deal 10000 Damage
Deal 50000 Damage
Deal 100000 damage
Win A Game With Only Pistols, No Classic Mode
Play 50 Matches
Damage Someone On The Last Bounce Of A Bullet
Win A Game With Less Than 25 Health