Contrast for effect: reality versus fantasy in games (specifically, MMOs).
I’ve been playing Lord of the Rings Online for a couple weeks (ok, only a few hours a week, but still…). It’s tons of fun, and moreso because my awesome wife likes it and plays with me!
I’ve only played a human so far, and at first I found the game environments a little bland. I guess having just finished the World of Warcraft trial, I was used to the bright colors and dense designs. I found LotRO to be much more sparse and less colorful. By sparse, I mean the designs are not cram-packed with tons of over the top details like giant weapons, huge armor, and fantastic creatures. (That’s a key point here.)
So the first good bit of the game, you are among humans and fight mostly normal animals and a few slightly fantasy creatures (though still in the realm of “realistic”). Playing this, while fun, was a little like quitting the Twinkies and eating raw veggies instead. It was kind of a shock, but it was still compelling, and I wanted more. 
But then we progressed farther and started to see the first fantasy creatures: goblins. I found myself really excited by them because they were very different from everything I had experienced before. Not wolves or spiders or huge flying insects, but real monsters! They had some camps in a marsh with bonfires at night, and it was really exciting.
This made me realize that most games, like WoW, give you such a constant and intense stream of eye candy and fantasy visuals that it all becomes kind of bland after a while. You meet another boss that looks incredibly cool, but your reaction is, “Meh.”
LotRO has used contrast to build up the fantasy elements simply by using them sparingly. I can’t imagine my excitement when I see something like a Black Rider or a Dragon! This is a powerful technique, and it won’t cost you more money or time to implement (other than planning how to pull it off with aplomb).
Because my wife and I started in a “normal” area without these elements, seeing them within that “realism” made them feel that much more fantastic. I’ve seen these kinds of things in games so many times before. Yet, here I was all giddy about it this time because I hadn’t been hit over the head with it to the point of being numb. I hope the rest of the game does this and uses the fantasy elements sparingly throughout.
I think this is a valuable observation for game developers. We should work to heighten contrast for maximum effect whenever possible. Less is more.