When you reach the point in the Freedom's Progress mission where you are told to place your teammates around the giant blast door, you can trick the game into spawning extra YMIR Mechs (Ed: But why would you want to ... ?). First, position your team accordingly, and watch the cutscene. You'll now be confronted by a Giant YMIR Mech. Instead of killing it, turn around, and head BACK through the blast door. This will glitch the game back before the cutscene. Place your team around the blast door again, and the cutscene will play. This will spawn an extra YMIR Mech. Repeat as many times as you wish, but more than three YMIR Mechs will most likely kill you!