Monster Hunter 4 is a new game being produced by Capcom. It is the second game in the Monster Hunter series to be released on the Nintendo 3DS. There is a stronger emphasis on platforming than before, walls can now be climbed more fluidly and in any direction, and for the first time Hunters can grab onto monsters and attack them. Environments shown also appear to be larger than before - possibly even open-world.
Various monsters have been confirmed to return, most notably Rathalos, Rathian, Tigrex and Yian Kut-Ku.
It was later revealed here that the entirety of the original teaser trailer was playable.