In my opinion It looks to me as if it is a fighting type but quite different as you can play as coop of up to four players to defeat a certain enemy.
That's based on the trailer below. I just read what Hack and Slash means and wikipedia says it is a close combat with short-range weapons.
I haven't tried a similar gam e like this but I am planning to play it as I am quite intrigued how it is played and for me to be able to write something.
I may update this once I get that chance of playing.
In the interim you may want to gather infos from the Official Site
Name: Dynasty Warriors.cso
Size: 1.1GB (1132776335 bytes)