Making a good game takes intense skill, a creative mind and in many cases a desire to experiment and take risks. Some of the best games are games we don't expect or that show us things we've never seen before. Portal is the go to example, in that it took the FPS and literally turned it on it's head, instead creating a physics based puzzle game, something we'd never really seen before. If the creator(s) successfully achieves this combination- interesting and creative mechanics, solid and accessible game-play, a compelling story and so on, a decent game is the result.
For me personally, what can take a game to new heights and turn it from good to great, is the soundtrack. And by soundtrack I don't necessarily mean the audio, but the music or lack-of, that accompanies the product.
Like in film, music can really leave it's mark when used correctly. It can build tension, create a sense of chaos and move the player nearly as much as the action on screen can (if done well). But one thing it does to me is have a lasting impact.
Some of my favourite games have brilliant and memorable soundtracks, that when heard independently from the game bring back memories of specific moments and events that happened in game worlds either whilst I was playing alone or with friends.
Music that comes to mind is strangely the soundtrack to GTA San Andreas. It may be that I played the game so much all those years back that the songs from the in-game radio have logged themselves in my mind, however every time I hear one of them it makes me think back to driving through the fictional American state. And what's more is that not only do I love those songs, but from listening to the eclectic mix of 90s hip-hop and classic rock, I have discovered artists and albums that perhaps I wouldn't have without playing the game in the first place. Public Enemy, David Bowie... a couple of the artists I now listen as a result. And I know for a fact that such an experience is not unique.
IGN recently interview Chain Gang of 1974, an group of musicians who's track was part of the soundtrack to the latest GTA, funnily enough the return to the state of San Andreas, and who've experienced a huge amount of success as a result. People have identified their music and come to like it, just as I have, through the game.
In many ways the game industry, like the film industry, is helping music become ever more mainstream. It introduces people to new things and is a great avenue for discovering new talent. Artists are now increasingly being asked that their songs appear in adverts for games (Woodkid songs in Assasins Creed for example) as well as their soundtracks, a benefit to both the makers and the musicians. It will be interesting to see how the relationship progresses.
All in all though, when done right, the game and the music can work seamlessly together creating a great overall experience that generates long lasting memories.