The 'Hidden Fronts' Multiplayer Map Pack 2 Add-on for Gears of War has 5 achievements worth 150 gamerscore.
Win a multiplayer match of 3+ rounds in any game type on 6 different downloadable maps
Win 20 multiplayer matches of 3+ rounds in any game type on the Garden multiplayer map
Win 20 multiplayer matches of 3+ rounds in any game type on the Subway multiplayer map
Win 20 multiplayer matches of 3+ rounds in any game type on the Bullet Marsh multiplayer map
Win 20 multiplayer matches of 3+ rounds in any game type on the Process multiplayer map