No one is limiting anyone on anything. If someone wants to play an X-men character by all means please do It'll make this arc move faster if not nothing is stopping you from doing something else. No one has been telling anyone who they can or can't play. Participation-wise Red Robin and Gallagher is playing last I checked. They've just been waiting for me. As for explaining what going down its pretty simple. Warren starts development of a mutant cure via his company. Fallen attacks Warren, defeats him, and take his place. Fallen plans on using the cure against the world. X-men will eventually stop him. Thats it. Why is this a problem?