Along the way we're also hoping to improve upon the things we didn't like about Blood, and add a few new ways to look at the genre in general. It has to be satisfying and challenging, without needless frustration. I think if you look at any great game you'll find that at its core it is extremely focused in the style of gameplay it goes for. Practically any idea can be made fun, but the gameplay has to be well-conceived and thought out. I think a game based around realism could be made and could be great, but it's going to play very differently from something like Quake.
Realism tends to make for a much more strategic game, versus a fast-paced one.
Simply adding realism to a game like Quake is in my opinion a mistake, because it contradicts what the game is going for in the first place. I wish people were making more shooters aiming for realism, like Goldeneye and Outlaws, because we have plenty going for fast action, but I don't think watering down a fast-paced game with realism is the answer. Blood 2 is going for an extremely fast pace, so we take LOTS of liberties with realism, but we do it on purpose, for the gameplay. The main disadvantage has been developing the engine, Shogo, and Blood 2 all at the same time, and having to compete with titles that are primarily using finished engines, or have had 3 or 4 years of development and hype. Shogo and Blood 2 will be awesome, but they'll be nothing compared to the next generation of Lithtech games.