In Swarm mode if you get caught by the bigger aliens you are dead. I mean, DEAD. You can't shoot them (they seem to be too near to get hit by anything) an you can't run from them. Then the wave counter reset any time you die AND you respawn in the middle of the enemies that killed you. Finally they added the swarm badge that is a prerequisite for completing the 2012 Halloween quest, making that unwinnable. This just seems unfair.
Finally this one got badges!
This game has quite an original concept and the "storytelling" feel is appealing. The negative point is that the "hero" phase is too much simple for my tastes (just 4 hero endings...).