Gamasutra has an interesting article about Establishing an Aesthetic in Next Generation Sound Design.
Given that sound designers and composers now have so much more freedom to overproduce and over-implement sound for videogames, methods of limitation will become necessary in order to differentiate the sounds of one game from another. How can we begin to make better sound in this seemingly limitless age by using less? It begins with realising that it is how we approach technical limitations as composers or sound designers that forms the very core of our art. The second thing to realise is that we have greater limitations than the fully equipped million dollar studio, and this gives us a distinct advantage. The limitation with expensive studios is cost, so usage time is bounded, however with the rise of the professional quality home studio and inexpensive digital equipment, cost has become less of an issue. All we need to do is recognise and capitalise on our limitations and avoid some of the easier traps to fall into. It is all too easy to create high production quality audio while ignoring the greater goals of high artistry and meaningful work. Instead of being able to identify the particular platform by playing a particular game, we should be able to have a good idea of who the audio team was behind the game and their style they have impressed upon the audio. The style we choose four our audio should be as distinctive and recognizable as the visual style of the game.
This whole process begins with establishing the limits you wish to work within. This is what will define your ‘aesthetic’.