Here is the full list of all 50 Beat Blast achievements.
Defeat a boss with 1 heart remaining
Defeat the Seed with Automelodic and Plagued challenge modifiers active
Destroy ten or more enemies with a single Bazooka shot
Die for the tenth time
Hold 500 or more bits at one time
Have six or more turrets active at a time
Play with the Escape Artist and Power Saw abilities at the same time
Get 10 or more stacks of a single passive ability
Defeat an elite enemy with a single critical hit
Defeat every enraged boss
Play with the Sword and Riot Shield abilities at the same time
Acquire 24 or more notes in a single run
Chain 3 or more dodges together
Play with the Fortify, Riot Shield and Barrier abilities at the same time
Block a laser with Riot Shield
Defeat the Seed with a difficulty rating of 1.0 or higher
Defeat the Seed with the Operation and Super Spot challenge modifiers active without touching a wall
Participate in a competition
Unlock ten abilities
Defeat your first enraged boss
Have 6 or more enemies slowed, poisoned or stunned at the same time
Defeat the Seed with Spiral Bullets
Earn a timed reward
Acquire a legendary ability
Defeat the Sentinel
Defeat every boss
Have a power note, offensive equipment and defensive equipment at the same time
Acquire a curse from the black market
Find your way out
Defeat the Seed
Defeat Meg&Byte
Collect 30 sound pickups
Defeat Queen Bee
Buy everything in a store
Upgrade a power note
Clear the first level without taking damage
Defeat the Giant Snake
Defeat a boss using the Sword
Unlock your first ability
Die for the first time
Have all four note colours equipped to your song at once
Dodge through an enemy or an enemy projectile
Complete the tutorial
Defeat a boss in under 60 seconds in Compete mode
Unlock everything
Clear the first two levels without taking damage
Clear the first three levels without taking damage
Clear all four levels without taking damage
Defeat a boss or miniboss while under the effects of a shrine
Unlock every challenge modifier in Play mode