I completely love playing and designing games and always will. I am so into games that I listen to game music all day. That may sound strange, but you can guarantee I'm a hardcore gamer and would never let you down by designing a crappy title.
I think DOOM had just the right mix of elements that keep people coming back to it: great monsters, excellent weapons with great balance, a spooky environment and extreme speed.
In marketing I've seen only one strategy that can't miss - and that is to market to your best customers first, your best prospects second and the rest of the world last.