Here is the full list of all 56 Gears of War: Ultimate Edition (Windows) achievements worth 1,250 gamerscore.
Killed a Berserker in the Conservatory
Delta found downed chopper
Deployed the Sonic Resonator
Killed a Corpser
Recovered 22 COG tags
Delta descended into the mines
Reunited with Baird and Cole inside the Imulsion Factory
Read one full comic
Defended Stranded Settlement and headed to Lethia Imulsion Factory
Got the Junker at Chap's gas station
Used the spotlight as protection from the Kryll
Made a Deal with Franklin
Killed the Berserker in the Tomb of the Unknown
Recovered 11 COG tags
Rescued Damon Baird from the Tomb of the Unknown
Rescued Augustus Cole in the House of Sovereigns
Reached level 10
Reached level 5
Performed 5 perfect active reloads in a row
Performed 25 perfect active reloads
Finished playing a Versus match
Played one Versus Match with a Custom Weapon Skin
Escaped from the Slab
Completed tutorial path on any difficulty
Story progression in Act 5 Chapter 8 (on any difficulty)
Story progression in Act 5 Chapter 6 (on any difficulty)
Win a match in every Versus map (social or competitive)
Win 25 matches in Team Deathmatch
Defeat General RAAM in co-op on Insane without either player being DBNO
Win 10 Versus matches without losing a round (social or competitive)
Complete all acts on Normal Difficulty
Kill 3 enemies at once 10 different times (on any difficulty)
Reach level 25
Complete all acts on Insane Difficulty
Win 25 matches in Boxes (social or competitive)
Complete 1 co-op chapter in co-op (on any difficulty)
Complete 10 different chapters in co-op (on any difficulty)
Finish with the highest point in a Versus match (social or competitive)
Spot 100 enemies ending in a kill in Versus (social or competitive)
Revive 100 teammates in Versus multiplayer (social or competitive)
Recover all 33 COG tags (on any difficulty)
Complete 100 matches in ring-based game types on Xbox Live and capture 3 objectives in each match
Complete all acts in co-op (on any difficulty)
Story progression in Act 4 Chapter 6 (on any difficulty)
Story progression in Act 5 Chapter 3 (on any difficulty)
Kill an enemy with every weapon in Versus (social or competitive)
Complete all acts on Casual Difficulty
Win a match in every Versus game type (social or competitive)
Win 20 rounds in ring-based game types on Xbox Live by shutting out the opposing team
Story progression in Act 5 Chapter 2
Close all 4 e-holes around the fountain in Fish in a Barrel without any Locust fully emerging
Reach level 100 and re-up
Kill 10,000 people in Versus matches
Complete all acts on Hardcore Difficulty
Story progression in Act 5 Chapter 5 (on any difficulty)