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