Full list of all 78 Gears of War 2 (JP) achievements worth 1,750 gamerscore. It takes around 300-500 hours to unlock all of the achievements on Xbox 360.
Train the rook (any difficulty)
Story progression in Act 1, Chapter 2
Story progression in Act 1, Chapter 4
Story progression in Act 1, Chapter 6
Story progression in Act 2, Chapter 4
Story progression in Act 2, Chapter 5
Story progression in Act 2, Chapter 6
Story progression in Act 3, Chapter 3
Story progression in Act 3, Chapter 4
Story progression in Act 3, Chapter 6
Story progression in Act 4, Chapter 2
Story progression in Act 4, Chapter 3
Story progression in Act 4, Chapter 6
Story progression in Act 5, Chapter 1
Story progression in Act 5, Chapter 2
Story progression in Act 5, Chapter 4
Story progression in Act 5, Chapter 5
Complete all campaign acts on Casual Difficulty
Complete all campaign acts on Normal Difficulty
Complete all campaign acts on Hardcore Difficulty
Complete all campaign acts on Insane Difficulty
Recover 5 collectibles (any difficulty)
Recover 20 collectibles (any difficulty)
Recover all 41 collectibles (any difficulty)
Complete 1 chapter in Co-op on any difficulty (Marcus or Dom)
Complete 10 chapters in Co-op on any difficulty (Marcus or Dom)
Complete all acts in Co-op on any difficulty (Marcus or Dom)
Win 10 chainsaw duels (any mode)
Use a meatshield to save your life 10 times (any mode)
Kill 30 enemies with a cover mounted Mulcher (any mode)
Kill 30 enemies with the heavy Mortar (any mode)
Kill 10 enemies with a planted grenade (any mode)
Melee 10 enemies down with the Boomshield equipped (any mode)
Kill 30 enemies with the Scorcher Flamethrower (any mode)
Perform 30 perfect Active Reloads (any mode)
Melee 30 Tickers (any mode)
Kill an enemy with every weapon in the game (any mode)
Perform all 11 unique executions on a downed enemy
Kill 100,000 enemies (any mode)
Win 3 matches of Wingman (public)
Capture 10 meatflags in Submission (public)
Win 10 rounds of Guardian as the leader (public)
Win 3 matches of King of the Hill (public)
Successfully complete the 5 lessons of multiplayer Training Grounds
Kill 10 enemies with a grenade while down but not out (any mode)
Play 1999 rounds of multiplayer (any mode)
Win a multiplayer match on each of the 29 shipped maps (any mode)
Survive the first 10 waves of Horde (any difficulty, any map)
Survive all 50 waves of Horde (any difficulty, any map)
Complete waves 1 through 10 in Horde on all 29 shipping maps (any difficulty)
Complete waves 1 through 50 in Horde on all 29 shipping maps (any difficulty)
Play a multiplayer match on all 29 shipping maps
Earn enough multiplayer experience to reach level 5 (Horde or Public only)
Earn enough multiplayer experience to reach level 8 (Horde or Public only)
Earn enough multiplayer experience to reach level 10 (Horde or Public only)
Earn enough multiplayer experience to reach level 12 (Horde or Public only)
Earn enough multiplayer experience to reach level 15 (Horde or Public only)
Earn enough multiplayer experience to reach level 20 (Horde or Public only)
Earn enough multiplayer experience to reach level 25 (Horde or Public only)
Earn enough multiplayer experience to reach level 30 (Horde or Public only)
Earn enough multiplayer experience to reach level 35 (Horde or Public only)
Earn enough multiplayer experience to reach level 40 (Horde or Public only)
Earn enough multiplayer experience to reach level 45 (Horde or Public only)
Earn enough multiplayer experience to reach level 50 (Horde or Public only)
Earn enough multiplayer experience to reach level 55 (Horde or Public only)
Without being detected, complete the "Road to Ruin" deleted scene after choosing the stealth option
Complete the "Road to Ruin" deleted scene after choosing the guns blazing option
Complete the "Road to Ruin" deleted scene in co-op as either Marcus or Dom
Earn enough multiplayer experience to reach level 60 (Horde or Public only)
Earn enough multiplayer experience to reach level 65 (Horde or Public only)
Earn enough multiplayer experience to reach level 70 (Horde or Public only)
Earn enough multiplayer experience to reach level 75 (Horde or Public only)
Earn enough multiplayer experience to reach level 80 (Horde or Public only)
Earn enough multiplayer experience to reach level 85 (Horde or Public only)
Earn enough multiplayer experience to reach level 90 (Horde or Public only)
Earn enough multiplayer experience to reach level 95 (Horde or Public only)
Earn enough multiplayer experience to reach level 100 (Horde or Public only)
Kill 25 Bloodmounts with a Scorcher while playing Horde (any difficulty)