It may just be me but I think that nowadays the industry seems to be spending too much time on realism and forgetting what makes games great - having fun. I think the second last level in halo 3 is a prime example. I won't give anything away to those who haven't played, but I found myself very bored and it just wasn't an enjoyable experience. Other games are guilty of this too. The problem is that gamers have forgetten why they play games and don't mind slogging through a repetetive, gloomy corridor shooter, just because the graphics look good.
The wii has the right idea in its new approach but I still don't think they've quite nailed it. They've gone too far the other way, in that many of their games are just too casual orientated / minigame collections. Games need to try the middle approach, where they can still push for great graphics, audio and realism, but can deliver an experience that is innovative and fun. I think the best games tend to be ones thatdare to do something different.We've just about passed the world war two phase, but too many games stillseem to be aiming for the bogstandard shooter title.
Games like the Katamari series, whilebeing nowhere near the standardof some other games, are great because they are completely different to anything else that's currently out there. But on the other end of the spectrum, I just played the Call Of Duty 4 demo and that was extremely fun, because it's so immersive and intense. Multiplayer is another way games can be fun. Nothing beats playing co-op on a really great game, because it sucks you in to the experience and makes it much more exciting and enjoyable.
Other factors are important, but having fun is what makes a game truly stand out.