Here is the full list of all 12 Cosmic Carnage Demo achievements.
Unlock Carnage Level 3
Unlock Carnage Level 4
Unlock Carnage Level 2
Unlock Carnage Level 5
Unlock the singulary upgrade tree
Unlock astronaut verdell
Unlock the shredder upgrade tree
Unlock the scatter ship
Unlock the raggo ship
Unlock the laser upgrade tree
Unlock the dashing astronaut "Skye"
Unlock the wave upgrade tree