Well, I've been thinking about this a lot. I'm going to be covering these topics below:
*NOTE* a few members might have trouble understanding this thread properly. I'll put this at the top so they can read it, instead of not caring to actually read my thread at all. I've already had one. This is not "IT WILL" make a good game thread, it is a "WHAT CAN" make a good game thread. I stated in almost every topic "many gamers" Implying that not everybody likes the same things.
Lets start out with Physics.
Physics in games mean a lot to many users because they always want to see that building fall, or dig a hole in the ground. Although that is a lot to ask for, even simple physics are essential to games and (of course) gamers. Simple physics such as pushable objects via vehicles, explosions. These are usually included in every game, but in ArmA II, simple physics are evident, but just don't cut it. Rolling something over is very hard, if not impossible, almost no matter how hard you hit it. If your plane hits the ground head-on, you die (of course!) but the plane just stops right in the ground. Like nothing happened. The plane should at LEAST dig into the ground a few feet, which in many games is called penetration, which is demonstrated in the novodex demos. If a object hits another object to a static object or ground, it will or usually will go a little inside the static object.
Advanced physics, such as Water physics, volumetric smoke/fog/cloud/gas physics, procedural destruction, land modification, and structure demolition physics are what gamers really love.
Water Physics simulate water, and how it moves around geometries, and itself. You don't have to simulate a whole ocean, just the top of it is fine. Same with pools. Small quantities which require less particles, such as tubs, sinks, buckets, oil barrels and such may be filled completely with water. This allows the player to spill these objects, and eventually empty them, all simulated realistically. Water Physics can also include currents and waves.
Volumetric Gas can play a large part in games. Mirrors edge demonstrated this, with gas that you could move, and block, showing that it can move around the player and objects around it. It can also help in games that simulate flight, such as Flight simulators and generally shooter games, like ArmA 2. Volumetric clouds allow the player to see clouds as a 3D object, rather than a rotating 2D photo/texture, and when flying through you can tell its 3D.
Destruction plays a very very VERY large part in games. Structure destruction is almost essential to any gamer. Check out Red Faction Guerrilla, this game allows complete destruction of almost every structure in the game, and its all done via realtime physics, and you can NEVER destroy something the same way. This really adds to the immersion in the game. A lot of gamers just love seeing that 4 story building collapse the way they wanted it to, or that bridge with all those cars go down. Terrain destruction is basically modification of the terrain. This is demonstrated perfectly in Red Faction (1) Which let you blow holes in the earth/walls with explosives. If you were good enough you can even mine your way to the end of the level. This really would be a good feature in lots of defensive and war games, as you can basically drop a C4 on the ground, blow it up and hide in your bunker/trench you just created. It is very addicting.
Why are physics important to gamers?
Physics add to the immersion by allowing the player to relate to what should happen, and what happens in game. This allows the player to make that connection, thus usually making the game addicting, and fun.
Sound is a very important aspect of a game, because it allows the player to feel like he's there. Sounds are recognized by the player, and because sound is a sense, usually makes the player "feel there". Good games would have high quality, real recorded sounds (or at least cool sounding audio for those sci-fi games). They also usually include sound physics, which usually means that it takes time for sound to travel. It can also mean (as well) that sound can bounce off walls (e.g. Proper reverb which I do NOT see in games!!!), and affect objects. (if a sound is very load, it may push the object or shake it. Yet to see this though..)
Graphics can mean a lot in games, and to many gamers. Seeing games look nice not only allows the user to relate the scene to reality, but generally is just "eyecandy". Not many people like to see Crysis on low, or medium after seeing very high? I don't think anybody likes to see jagged edges too much, and incorrect shadows.
Shadows and lighting play a very big role in graphics, mostly because you can see that the light is hitting an object, but is either not making a shadow, not making the shadow in the correct position, or making a weird looking shadow for the lighting type. Ray Tracing basically ends all these problems, as from what I've read, it simulates how light really hits surfaces. A lot of games I've seen recently have too much bloom, which can be very distracting.
Textures can mean a lot, too. Too weird looking textures may have the user confused on identifying what they are. Too low res textures look pixelated (duh!) and can make gamers unhappy.
Gameplay includes AI, movement.. and much more. AI plays a massive role in lots of games. AI basically is how the non-player reacts, and does things. Lets take Operation Flashpoint Dragon Rising as an example. Good AI traits in this game are how the AI units move, and shoot. The AI moves very smoothly in buildings, walks around normally, doesn't hit walls or do anything stupid. If you are in front of them, they react fast, they either shoot you, or go to cover. (enemy example here). Some bad traits are how the AI can be too smart, they can kill you much easier than the best player could. This can be horrifying when you fly helicopters, as the anti air units can shoot you down way too easily. Very frustrating.
Movement can mean a lot in many games. You don't want to have the player/unit running into too many obstacles/objects, as it makes it frustrating for the gamer that he can't get somewhere without moving around a maze of objects. Ways to get around this is the ability to jump, vault/climb them, or just remove objects entirely. This applies to RTS games as well, as I've played a few games where it takes a while for some units to navigate around towns and bases that are not easily accessible. (e.g. roads are not good, or they don't even follow the roads at all or if there is any).
I won't quite go any deeper with gameplay, as it is a very broad subject.
You've got to have a good story, or else gamers just don't feel like they are immersed. There are two things devs should worry about: the actual story (usually is epic, has history, and future. (to create sequels)), and story injection. (How it is implemented) in the game A good example of a bad story injection is red faction guerrilla. It was a great game, but the game was over very quick, and there was not much of the red faction storyline in there. It was "blow this up" then a few mentions about red faction, then "blow this up". There were missions, but there should be more. A good story example would be Fallout 3. You're in a post apocalyptic world, which is very hard to avoid, and gives the devs lots of choices and ideas. There are lots of things that gamers like to see, like vaults (basically bunkers for people to stay in during the Apocalypse (safely)) that you can explore and learn about, and refers to things you hear in missions.
*THREAD UNDER CONSTRUCTION!!*
So OCN, what do YOU think makes a good game?