- Completed the Campaign on Normal difficulty
- Completed the Campaign on Heroic difficulty
- Completed the Campaign on Legendary difficulty
- Completed every mission in Halo: Reach alone, on Legendary
- Completed the 2nd mission on Normal or harder
- Completed the 3rd mission on Normal or harder
- Completed the 4th mission on Normal or harder
- Completed the 5th mission on Normal or harder
- Completed the 6th mission on Normal or harder
- Completed the 7th mission on Normal or harder
- Completed the 8th mission on Normal or harder
- Completed the 9th mission on Normal or harder
- Completed the 10th mission on Normal or harder
- Cleared the 2nd mission without setting foot in a drivable vehicle
- Killed 2 vehicles at once with the Target Locator in the 3rd mission
- Hijacked a Banshee during the Reach Campaign
- Killed the Elite Zealot before he escaped during the 5th mission
- Performed an Assassination against an Elite to survive a fall that would've been fatal
- Destroyed the Corvette's engines & escort in under 3 minutes in the 6th mission on Heroic or harder
- Finished the 9th mission on Legendary with the Scorpion intact
- Earned a Triple Kill while Jetpacking in Campaign, Firefight or Matchmaking
- Killed 7 Moa during the 2nd mission of the Campaign
- Killed 3 of the anti-aircraft batteries during the 8th mission
- Used a Health Pack to replenish life after taking body damage
- Performed an Assassination on an enemy
- Killed 10 enemies in a Firefight or Campaign session with the M6G pistol
- Killed 10 enemies in a Firefight or Campaign session with the DMR
- Traded weapons with an AI ally in Campaign
- Killed 10 enemies in Firefight or Campaign with a supercombine explosion
- Let a teammate spawn on you 5 times in an Invasion Matchmaking game
- Earned a First Strike Medal in a Matchmaking game
- Won a game of Invasion in the 1st phase
- Earned a Killing Spree in multiplayer Matchmaking
- Earned a Killionaire medal in Firefight
- As an Elite, killed 5 Spartan players in Matchmaking
- Scored 15,000 points in Score Attack Firefight Matchmaking
- Scored 50,000 points in a Firefight game
- Scored 200,000 points in a Firefight game
- Scored 1,000,000 points in a Firefight game
- Completed a Firefight set on Legendary without dying
- Purchased an item from the Armory that required the rank of Lt. Colonel
- Reached the rank of Corporal in the UNSC
- Reached the rank of Captain in the UNSC
- Used the File Browser to upload a file to your File Share
- Completed all of the Daily Challenges in a given day
- Purchased an item from the Armory
- Recommended a file to someone
- Advanced a Commendation to a Silver state
- Completed a Weekly Challenge
http://www.areagames.de/artikel/detail/Alle-Achievements-aus-Halo-Reach-im-Detail-enthuellt/109642