Full list of all 12 Rocket Knight achievements worth 200 gamerscore. It takes around 15-20 hours to unlock all of the achievements on Xbox 360.
Completed Gold Sparkster Mode
Completed Arcade Mode on Hard within 60 minutes
Completed Arcade Mode scoring 1,000,000 or more
Completed Arcade Mode on Hard in a Single Playthrough
Defeat 3 enemies with a single reflected projectile
Completed all stages below par time
Completed 2.1 having collected all pickups
Defeat 5 enemies in a single Rocket Burst or Drill attack
Completed 3.2 without taking damage
Completed Arcade Mode on Normal
Completed all stages
Completed 1.2 having defeated all enemies