Arkham Horror: Final Hour - Overview in 60ish Seconds by the Arkham Chronicle

About Arkham Horror: Final Hour, from BoardGameGeek:

You arrived too late to stop the loathsome rite, and a monstrous, transdimensional Ancient One tears through reality. An iridescent rift slashes across the darkened skies, heralding the nightmarish creatures that pour into the hallowed buildings of Miskatonic University. As howls and screams cut through the night, there is only one path left for your fearless investigators-hold back the horde long enough to somehow reverse the summoning. Arkham Horror: Final Hour is a fully co-operative, fast-paced board game for one to four players. An endless tide of monsters sweeps across the Miskatonic University campus, and you must hold them back, all while searching desperately for the ritual components you need to put an end to this insanity. Playable in under 60 minutes, your fate depends on cooperation between you and your fellow investigators. The odds against you are astronomical, but if you don't succeed, this will indeed be the final hour for Arkham...and the world. -description from the publisher