Full list of all 12 Gotham City Impostors achievements worth 200 gamerscore. It takes around 40-50 hours to unlock all of the achievements on Xbox 360.
Accept your first Promotion.
Kill ‘em, fumigate ‘em, and pysch ‘em out… all over Gotham.
Complete all feats related to a particular loadout weapon.
Complete all feats related to a particular gadget or support item.
Earn 50 gold medals in Challenge mode.
Become a Nemesis 50 times.
Kill 50 enemy players using the panic-slap melee attack.
Turn the tables in Fumigation when the enemy team's victory is imminent.
Earn a 10-kill streak.
Complete the Initiation mission.
Finish one match of Gotham City Impostors.
Unlock any locked loadout or costume item.