Gears of War 2 introduced us all to Horde mode where four players work together to survive against wave after wave of incoming enemy attacks that became increasingly difficult as the players progressed. Horde mode 2.0 in Gears of War 3 is set to improve on the original Horde mode in a variety of ways, such as offering bouts with huge boss creatures and mid-wave objectives.
One of the newest features in Horde mode 2.0 is fortifications. Players can build five different types of fortifications: barriers, decoys, sentries, turrets, and the silverback. In order to build fortifications, players will need to decide where they want to make their stand by building a command post. Once a command post is activated, all the player has to do is walk over to a green ghost image of a fortification type, and simply build the desired fortification. In order to build fortifications, you'll need to have enough money which can be acquired simply by killing enemies, which if you're playing Horde mode, is EXACTLY what you should be doing.
The video touches on some other subjects such as what else besides building fortifications players can do with their cash and a number of other things that I'll leave the video to explain.