For people who have never played pen and paper games, it's pretty much like a group of friends all creating a verbal story together which is governed by game rules and random chance. Sometimes also uses counters to represent characters and paper/card templates to represent dungeons etc to bring some form to the overall scope. It's descriptive like listening to an audio book when you're not participating and just listening. It's more fun to play than to listen or watch and even listening and watching in itself is enjoyable. I really enjoy FFG role-playing games. Dark Heresy is going though a second edition release I believe as well. Their Warhammer 40 000 role-playing games are the closest you can get to a full on emersive experience in the Warhammer 40K universe yourself and friends can get using your imagination. I haven't played Dark Heresy, but I have played Rogue Trader and Deathwatch. Very well built Pen and Paper games. The closest thing to a Pen and Paper game in a video game sense would be a MUD.