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
Place yourself in the top ten of the leaderboards
Reach 1500 points
Destroy at least 15 blocks at once by gravity change
Achieve combo 6 or higher
Destroy at least 5 iron blocks using TNT or Big TNT
Craft at least 4 powerups in one game
Destroy 7 blocks in one line (without using powerups)
Finish arkanoid minigame without failure
Destroy line during invisibility
Destroy the threat block just before activation
Destroy 4 or more blocks in one row
Use at least 9 powerups in one game
Destroy a threat block using a powerup
Use your first crafted powerup
Clear the game board at level 10 or higher
Use all types of powerups (standard and crafted) during single game
Reach 500 points without changing gravity
Achieve level 100
Destroy all irons at level 20 or higher (Simple Mode)
Reach rank 20 (Coming soon in Anniversary Update 1.3)