Here is the full list of all 41 Supreme Commander achievements worth 1,000 gamerscore.
UEF Campaign Complete: Easy
UEF Campaign Complete: Normal
UEF Campaign Complete: Hard
Aeon Campaign Complete: Easy
Aeon Campaign Complete: Normal
Aeon Campaign Complete: Hard
Cybran Campaign Complete: Easy
Cybran Campaign Complete: Normal
Cybran Campaign Complete: Hard
Complete the tutorial.
Build 1000 ground units.
Build 1000 air units.
Build 1000 sea units.
Kill 1000 air units.
Kill 1000 ground units.
Kill 1000 sea units.
Destroy 500 buildings.
Produce 1,000,000 power.
Produce 1,000,000 mass.
Produce 100,000,000 power.
Produce 100,000,000 mass.
Beat Normal AI on all Skirmish maps.
Beat Challenge AI on all Skirmish maps.
Beat Supreme AI on all Skirmish maps.
Kill 100 ACUs.
Build 1000 buildings.
Build 1 experimental unit for each faction.
Build 100 experimental units.
Fire 10 nukes.
Fire 100 nukes.
Kill 100 units with Point Defense Turrets.
Kill 100 units with Anti-Air Turrets.
Win on all Assassination maps on any difficulty.
Win on all Annihilation maps on any difficulty.
Win on all King of the Hill maps on any difficulty.
Win on all Command Point maps on any difficulty.
Win on 10 different multiplayer maps.
Capture 50 enemy units.
Capture 100 enemy units.
Win on all multiplayer maps.
Finish all campaigns on all difficulties.