I think I’ve mentioned something like this earlier, but I gotta make a remark about this now. It’s about those tiny details in games. I’ve recently spend some time playing Left 4 Dead and Grand Theft Auto 4 (thanks people) and both of these games have all these tiny details that make them really fun to play.
In L4D, there’s all those noises that occur (hunter walking nearby), the doors break nicely (and leave a hole), characters shout “stop doing that” (or something similar) when they got hurt by friendly-fire. Plenty of particle effects. Flashlight works nicely since it’s attached to the gun (so when you are reloading your weapon, the light moves around the room). So many things (and some of these actually affect in gameplay).
In GTA 4, you can see leaves floating in air when they are dropping from trees. It’s a small detail that has no impact in gameplay, but it’s nice to watch. There’s several radio channels to choose from (and there’s plenty of recorded voice, it feels like a real radio). You can even watch television (with several channels) in your room. All these tiny details mean nothing in terms of gameplay (you won’t get points for listening a radio show), but it makes the game much more immerse.
There’s so much ideas to gain by simply playing other games and thinking of all the tiny details that make game feel polished.