Here is the full list of all 21 3x64 achievements.
The base game contains 20 achievements, and there is 1 DLC pack containing 1 achievements.
Send your first replay to the leaderboard
Destroy line during invisibility
Destroy a threat block using a powerup
Destroy the threat block just before activation
Finish arkanoid minigame without failure
Use at least 9 powerups in one game
Craft at least 4 powerups in one game
Use your first crafted powerup
Destroy 4 or more blocks in one row
Achieve combo 6 or higher
Reach 1500 points
Clear the game board at level 10 or higher
Place yourself in the top ten of the leaderboards
Destroy at least 15 blocks at once by gravity change
Use all types of powerups (standard and crafted) during single game
Reach 500 points without changing gravity
Achieve level 100
Destroy at least 5 iron blocks using TNT or Big TNT
Destroy 7 blocks in one line (without using powerups)
Destroy all irons at level 20 or higher (Simple Mode)
Reach rank 20 (Coming soon in Anniversary Update 1.3)