Here is the full list of all 35 Aeon Must Die! achievements worth 1,000 gamerscore.
Clear the first Ivory encounter (Win or Lose)
Clear the Scarlet encounter (Kill or Spare)
Clear the Onyx encounter (Kill or Spare)
Clear the Ash encounter (Kill or Spare)
Reach the Aeon ending
Reach the neutral ending
Reach the good ending
Reach all endings in one save file
Complete all side story chapters
Lose all Purpose and let Aeon take control
Acquire all Aeon's Powers by buying them
Have 3 bike upgrades equipped
Reach an ending in a single save file without letting Aeon take full control or dying with honor
Kill an enemy by using a bike skill
Overheat an enemy and throw them to an assist row
Reach SSS rank on any mission
Reach S rank on any ending
Complete a revenge mission
Challenge Aeon in a Trial Within and win
Defeat Ivory on the first encounter
Use all of Onyx's attacks against them during the first stage of the Onyx encounter
Complete a chase sequence without getting hit during the Ash encounter
Complete the Scarlet encounter in under 2 minutes 30 seconds
Die with honor
Kill 13 enemies within 3 minutes in a single fight
Defeat Scarlet without becoming Overheated
Escape Ash's dimension with a perfect parry
Defeat Onyx's second stage without letting Onyx use any assist actions
Kill 13 enemies without becoming Overheated or Drained
Kill 13 enemies without getting hit
Complete all tutorials
Complete a single run without purchasing any upgrades (bike upgrades only)
In Rex's first encounter, kill all enemies before being killed
Reach the maximum level for all enemy attributes in a single save file
Destroy an enemy bike with an Overheated enemy