I didn't know what to expect before playing The Incredible Adventures of Van Helsing. I've seen the movie, but I don't remember much from it other than Wolverine fighting a lot of monsters. Luckily, that basic knowledge was all I really needed in order to understand what was happening in Van Helsing.
I believe the now common term to describe this genre is an Action RPG (ARPG), or in other words a "Diablo-like." These days ARPGs are fairly common: the divisive Diablo III, the mod-friendly Torchlight II, the free-to-play Path of Exile, and the upcoming Grim Dawn are all possible alternatives, so entering into the genre isn't exactly filling an empty void. Van Helsing definitely sticks to some of the core elements players have come to expect from an ARPG, and at least tries to spice things up along the way, even if it isn't successful.