They have multiple arms, making them vicious in melee combat, but sport no ranged attacks. You fight a group of purple, shark-looking aliens called Genestealers. They use pretty common weapons, so controlling them should be familiar to you. You play as fanatically religious marine-monks who pilot walking suits of armor called Terminators. Vengeance centers around two warring factions. The game doesn't appear to be using any pen-and-paper or RPG rules anyway, so you can consider this game 'inspired by,' but not a replication of, the tabletop experience. I must admit that I am not familiar with them, so I'm approaching this review from a strictly video game standpoint.
Space Hulk: Vengeance is based off of the Warhammer 40K tabletop games created by Games Workshop.