As someone who hasn't got a clue about Warhammer, I left the Gamescom demo of Space Hulk: Deathwing with a big smile on my face. This game is terribly promising and looks like something a group of friends could have a great time with!
For the uninitiated, a Space Hulk is basically a big collection of defunct ships in space. It's an adaptation of a tabletop game, so it's much like a dungeon. The interior is very much a daunting maze full of these disgusting little creatures called Genestealers, who want you dead ASAP. If you've ever played Warhammer: Vermintide or Left 4 Dead, they function in a very similar way to the rats or zombies, with certain variants causing you extra problems.
The thing is, it's different than both of these games in that you're not rushing along against waves. You have to always be ready to change your pace when surrounded by genestealers, blocking up pathways to stop them from completely overwhelming you. This is a problem, though, because as the developers told me, blocking up a door means that you've just lost a means to get out of the room. You are constantly being forced to enclose yourself to deal with the mobs of aliens out for blood.
I was shown the game in singleplayer, and the character was called a Librarian, which is one of the four classes you can play in the co-op mode. Librarians have psionic powers mixed in with devastating weaponry. There was a real focus on both ranged and up-close combat. Melee is very satisfying.
There are also psy gates, which serve as the main form of difficulty in Deathwing. You can deploy these teleporters to take you back to a safe spot, but they're limited by the difficulty you choose at the start of each mission. Of course, if you use less gates, you will gain a huge boost in score at the end of the level. This is tied to your progression and upgrades, so it's a risk you're going to have to take if you want to be the best damn Space Marine you can be.
Space Hulk: Deathwing is due this November for PC, and next year for Xbox One, and PlayStation 4.