Game aesthetics and realism

Nielsen goes over many game aestheics like screen space, time, graphical style, and sounds. These are all things designers must take into account when making a game
Games have evolved over time from having very primitive screen space to entire worlds in the game. In games like Pong, a single screen was all the game had. I've noticed that as games have gotten better, screen space has expanded. After Pong there were zone-based multi-screen spaces, where the trainsition isn't fluid, but it was enough to give the feeling of an adventure game. As time went on, games got more fluid and eventually reached 3D and the feeling of a seamless world. And even better, there were games where things happened even off screen like in RTS games like Command and Conquer. And then later, games that had things going on, even when you weren't playing--mainly MMO's. As games got more and more fluid and, the sense of realism increases dramatically. World of Warcraft feels like an entire world because of things happening all the time, and seamless transitions in a 3D world.
Time is also an issue with realism. Games that put a time limit on the game or force you to explore through the use of continuous scrolling game screen are not realistic at all. But games that happen in real time without any time limits do feel more realistic. "In Sim City, we might play for two minute of real time (play time), and two years could pass in the game world clock (event time)." The game is realistic in many ways, but the time factor reminds the player that they're still playing a game. This is opposite of a real time game like Call of Duty, where a minute in real life is a minute in the game. Once you shoot someone in the head, they die instantly. Things happen in real time, making the experience more realistic.
There are three graphical styles a game can be. The first is photorealism, where the game does its best to look like real life. The second is caricaturism, where the graphics "depart from reality" and as a result, the game feels more like a cartoon. And the third is abstractionlism, which is a visual style that doesn't represent people or real life objects. An example of this is Tetris. Nielsen says "abstractionalist games will probably for a long time be confined to low-powered devices like cell phones, or to experimental circles." I agree with this statement because games like this have no stories. If they did have stories, the game would most likely fall under the caractature category.
Finally we have the audio. Nielsen gives the categories of vocalization, sound effects, ambient effects, and music. Sounds are all pretty much self explanatory. The more realistic a sound is, the more realistic the game seems. But other things must also be taken account of. These are the environment, spatiality, and physics. A bear will sound different in an auditorium than in the woods. A car going 15 miles an hour will sound different than a car going 150. The randomness of ambient noises is also important. "'...the biggest tip off to the listenter that something is artificial is when the crow always caws just after the leaf rustles and before the frog croaks every thirty seconds or so.'" But it's not all about the realism. Music plays a huge role in games because of the sense of immersion you get. We don't have music that constantly plays in the background, changing to the mood you're in or what happens in your daily routine, but it's constant in all good games. It's not the most realistic thing in the world, but games would be boring without them. Plus you wouldn't say that a game wasn't realistic because music was playing in the background.
Even though we have the ability to make super realistic games, designers take a step back, sacrificing some realism in exchange for a more "gamey" feel. A good example of this is Viewtiful Joe. The graphical style is clearly more caricaturist, the audio includes a lot of cheesy sounds like the classic camera shutter or punching sounds that clearly don't sound like punches, and the game plays like a 2D scroller. The game is clearly unrealistic in pretty much every way, but it does it in a successful way. The point is that all these game aesthetics exist and the designers can take them wherever they want.

All games are different, but in general, besides rules, what's the most important thing to you in a game, in terms of aesthetics?