Here is the full list of all 56 Gears of War: Ultimate Edition achievements worth 1,250 gamerscore.
Reached Level 100 and re-upped
Defeated General RAAM in co-op on Insane without either player being DBNO
Won 20 rounds in ring-based game types by shutting out the opposing team
Completed 100 matches in ring-based game types and captured 3 objectives in each match
Revived 100 teammates in Versus multiplayer
Won 25 matches in Boxes
Won a match on every Versus map
Closed all 4 e-holes around the fountain in Fish in a Barrel without any Locust fully emerging
Killed 3 enemies at once 10 different times
Recovered all 33 COG tags
Won 25 matches in Team Deathmatch
Killed an enemy with every weapon in Versus
Spotted 100 enemies ending in an assisted kill in Versus
Finished with the highest points in a Versus match
Reached level 25
Won a match in every Versus game type
Defeated General RAAM
Completed all acts on Casual Difficulty
Completed all acts on Normal Difficulty
Completed all acts on Hardcore Difficulty
Completed all acts on Insane Difficulty
Completed all acts in co-op
Boarded the Imulsion bound train with the Lightmass Bomb
Killed the Brumak
Restored communications with Control
Restored power to the bridge
Escaped from the Brumak (end of Ch.6)
Discovered Adam's secret lab
Killed a Berserker in the Conservatory
Delta found downed chopper
Recovered 22 COG tags
Deployed the Sonic Resonator
Killed a Corpser
Delta descended into the mines
Reunited with Baird and Cole inside the Imulsion Factory
Defended Stranded Settlement and headed to Lethia Imulsion Factory
Read one full comic
Got the Junker at Chap's gas station
Used the spotlight as protection from the Kryll
Made a Deal with Franklin
Completed 10 different chapters in co-op
Recovered 11 COG tags
Won 10 Versus matches without losing a round
Reached level 10
Reached level 5
Finished playing a Versus match
Played one Versus Match with a Custom Weapon Skin
Killed the Berserker in the Tomb of the Unknown
Rescued Damon Baird from the Tomb of the Unknown
Rescued Augustus Cole in the House of Sovereigns
Completed 1 co-op chapter in co-op
Escaped from the Slab
Performed 25 perfect active reloads
Performed 5 perfect active reloads in a row
Completed tutorial path on any difficulty
Kill 10,000 people in Versus matches