Here is the full list of all 84 StarBreak achievements.
Lost 100 allies
Killed by spikes in the Fire Forest
Complete 20 midbosses
Kill 1000 enemies
Open a chest as a Spark
Killed by Fungus Cave boss mouth
Achieve MK II with any shell
Collected 100 Boosts
Destroy a Shell
Complete the Fire Forest
Complete the Tutorial
Register your account
Complete the Fungus Cave
Complete the Vanquished
Complete the Underground Base
Complete the Strands
Complete the Graveyard
Complete the Temple of the Lost
Complete the Star Cathedral
Complete the Elite Fire Forest
Complete the Elite Fungus Cave
Complete the Elite Vanquished
Complete the Elite Underground Base
Complete the Elite Strands
Complete the Elite Graveyard
Complete the Elite Temple of the Lost
Kill 20000 enemies
Deal a million damage
Complete all missions with a Wildfire
Complete all missions with a Duskwing
Complete all missions with an Ironclad
Complete all missions with a Fabricator
Get 10 impressive performance callouts
Get 100 impressive performance callouts
Achieve MK III with any shell
Achieve MK IV with any shell
Achieve MK V with any shell
Achieve MK VI with any shell
Complete 100 midbosses
Killed by Goldtooth
Killed by falling in Strands
Killed by Sweeper
Killed by Scavenger Tail
Killed by Stone Head
Picked up Prototype
Complete mission with less than 10 hp
Wear all Custom equipment
Wear all Experimental equipment
Wear all Prototype equipment
Make a purchase at a Secret Shop
Blocked 1000 Bullets
Blocked 100000 Bullets
Collected 10000 Boosts
Lost 10000 allies
Have 100 allies increase their MK
Have 10000 allies increase their MK
Have 20 allies complete a new mission
Have 1000 allies complete a new mission
Reach Wave 50 in the Underground Base
Reach Wave 50 in the Elite Underground Base
Find The Hidden Waterfall
Find The Mother Crystal
Find The Sympathizers
Find The Holo-Statue
Find The Embryo
Find The Bridge
Find The Chronicle
Find Bes
Find Horus
Find Ptah
Find Set
Find Thoth
Find Shu
Achieve A Rank with Wildfire
Achieve S Rank with Wildfire
Achieve A Rank with Duskwing
Achieve S Rank with Duskwing
Achieve A Rank with Ironclad
Achieve S Rank with Ironclad
Achieve A Rank with Fabricator
Achieve S Rank with Fabricator
Buy vanity item
Complete the Frozen Blight
Complete the Elite Frozen Blight