Could've been aliens, could've been a country having developed ultimate weapons, could've been anything imo. Dunno what trailer you saw, but I haven't seen anything that involved monsters.
I haven't read imdb or any site about it and now that I did I find it fucked up that a site like imdb would hand out such spoilers in the plot outline. The user comments all have to be checked with *** SPOILERS *** if they reveal anything so I dont see why the plot outline should be any different. Especially for a movie that tried to hide what it was about.
then you've seen a different trailer that I have so far, but besides that the comment "OMG I've seen it, it's huge!" could still be about a battleship, the ultimate soldier or an alien altogether :P
Just fan-art though. Nobody knows how it looks, except for those involved in the movie.
That was my first thought, when I saw the first trailer.
Five young New Yorkers throw their friend a going-away party the night that a monster the size of a skyscraper descends upon the city.
Which also suggests a monster.
Or so the trailer's say (A)
na, i think that it got a snake head :D