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.
Achievements they've won
Achievements they've not won
Earn 50 gold medals in Challenge mode.
Accept your first Promotion.
Complete all feats related to a particular loadout weapon.
Complete all feats related to a particular gadget or support item.
Kill 50 enemy players using the panic-slap melee attack.
Become a Nemesis 50 times.
Win each game mode in Ace Chemical, Amusement Mile, Crime Alley, Gotham Power and The Docks.
Earn a 10-kill streak.
Turn the tables in Fumigation when the enemy team's victory is imminent.
Finish one match of Gotham City Impostors.
Unlock any locked loadout or costume item.
Complete the Initiation mission.