Here is the full list of all 40 Last Encounter achievements.
One of your pilots needs to die.
Fill your second weapon slot.
Get some flight time under your belt.
You've reached the Materion galaxy.
You've reached the Gravitron galaxy.
You've reached the Solarium galaxy.
You've reached the Energion galaxy.
You've reached the Nova Space galaxy.
You've reached the Void.
Defeat the Dark Galaxy boss.
Defeat the Gravitron boss.
Defeat the Energion boss.
Defeat the Void!
You've killed what was left of Lea.
Skip any galaxy.
Skip galaxies 100 times.
Unlock a new pilot.
Unlock a new spacecraft.
Unlock 10 pilots.
Unlock 10 ships.
Have Lea available as pilot.
Fully research a weapon component.
Fill your third weapon slot.
Fully research a 2nd slot component.
Fully research a 3rd slot component.
Have exactly 666 credits.
Have more than 10.000 credits.
Complete a galaxy without dashing.
Complete a galaxy without taking damage.
Complete the Dark Galaxy 70 times.
Complete Materion 60 times.
Complete Gravitron 50 times.
Complete Solarium 40 times.
Complete Energion 30 times.
Complete Nova Space 20 times.
Confront Lea with Lea.
Clear all sectors before defeating the Void.
Use 20 different passive abilities.
Collect 1.000.000 credits.
Kill 10.000 enemies.