The September Update Title update for Gears of War 4 has 18 achievements worth 500 gamerscore.
Complete twenty Campaign Chapters (any difficulty)
Complete two Campaign Acts in Co-op (any difficulty)
Complete twelve Campaign Chapters (any difficulty)
Complete eight Campaign Chapters (any difficulty)
Complete seven Campaign Chapters (any difficulty)
Complete six Campaign Chapters (any difficulty)
Complete five Campaign Chapters (any difficulty)
Complete the Prologue in Co-op (any difficulty)
Complete four Campaign Chapters (any difficulty)
Reach Level 20
Reach Level 5
Reach Level 15
Earn 5 Ribbons
Reach level 2 in one Horde class
Upgrade 3 skill cards
Complete two Campaign Chapters (any difficulty)
Complete three Campaign Chapters (any difficulty)
Kill 25 enemies in Co-op Versus matches