Sound is such an invisible force in games. You don't really notice it whilst it's there, but if we were to take it away, you would surely see people quickly checking the audio options bumping up the sound levels and frantically cecking all the audio cables are still plugged in.
Now its not just the sound of footsteps and the realistic sound of brains splattering up a wall when you get a head shot with a 50. cal sniper that i'm talking about. I'm talking about the atmospheric and and epic scores that are composed just to make you cry, laugh sit on the edge of your sofa or other bum cushioning device. But before we get into the whole live orchestra sat in front of MGS4,I want to point out far in game sounds have come and affected our everyday lives.
Travelling home the other day I was just on the train to London, pretty boring and normal when all of a sudden I hear a few seats in front of me the mario coin collection sound go off and a guy picked up his phone ans started reading a text. Now pretty much everyone had looked up and a slight smile on their face remembering the Super Mario games and then immediately began to scowl at the crosswords they don't understand. Still on the subject of Mario, a great viral youtube video of a guy who took the original 8 bit sounding theme and thought it would be cool to beatbox it with a flute!
A little less recently another ringtone/ text alert sound caught my attention as the classic "!" MGS sound went off and I almost caught myself running for a cardboard box to hide under... well ok so its not all about making cool sounds for your phone, but games have really tried to make gaming a wholistic experience. Sound is a very emotional part of our sensory perception of things and can totally change the way we view dramatic moments and relate to events that happen in games. Halo in my opinion, really honed in on their music with large orchestral scores and grandious "LETS KICK ALIEN ASS!" style music to coincide with the games very dramatic intergalatic war based shooter. Uncharted 2 was something that was clearly inspired by the indiana jones scores and kept the music very tight to the way the environment and culture would be represented throughout the level. For example quite eery tibet throat singing was used throughout the creepy tibetan ice cave level in the hunt for the chitamani stone. Now i'd hate to say it but COD Modern Warfare 2 did have a few moments of great music to go along with the mindless killing of NPC's, especially in the Gulag level towards the end of the game (which by the way was totally stolen from the film THE ROCK starring Nicholas Cage and Sean Connery http://www.imdb.com/title/tt0117500/).
Little Big Planet is actually quite thoughtful in the way it allows you to create levels. I mean sure all the visuals and cool interactive effects are there to keep you entertained but they also give you a variety of soundscapes and the use of sound triggers They even went as far as allowing the characters you can make to have a sort of weird simlish language (http://en.wikipedia.org/wiki/Simlish) to communicate with you, with the help of added speech bubbles! I've created and messed around with the creation tools in LBP and the levels really only come to life when the sounds are added, which is personally the last thing I though would make the levels fun and totally made me realise how stupid I had been in overlooking the most basic of senses that I clearly take for granted!
Actually really good sounds to look out for are in Dead Space 2 well and the first one! That is a prime example of a game that without sound just wouldn't work at all. You can hear the necromorphs running through vents and the humms and buszzes of generators and the clangs of metal falling all help to make wet stains appear on the front of your trousers as there is nothing more scary than the sudden loud bang of a door opening next to you randomly and you can never tell if something is going to come running at you from the dark. Even the futuristic gun sounds are interesting, this is clearly a field waiting to be played in further and hopefully one that big composers can really influence the gameplay just as they influence the story and character in the film industry.