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.
Earn a 10-kill streak.
Unlock any locked loadout or costume item.
Finish one match of Gotham City Impostors.
Complete the Initiation mission.
Kill 50 enemy players using the panic-slap melee attack.
Accept your first Promotion.
Complete all feats related to a particular gadget or support item.
Complete all feats related to a particular loadout weapon.
Turn the tables in Fumigation when the enemy team's victory is imminent.
Win each game mode in Ace Chemical, Amusement Mile, Crime Alley, Gotham Power and The Docks.
Earn 50 gold medals in Challenge mode.
Become a Nemesis 50 times.