On game project length
Being involved in a game project requires lots of patience because it can take years for a project to finish. For example, I've been writing songs for Overgrowth for a few years now (since it was known as Lugaru 2), which is longer than most game projects I've worked on. The need for a composer isn't absolutely necessary in the early stages of game development, but it usually leads to better results. A playable demo isn't necessary for me to work -- I just need a list of music tracks along with some concept visuals and gameplay information. Here are some excerpts from combat songs I wrote based on Overgrowth concept art and Lugaru gameplay:
I start composing a song by using a keyboard to develop the melody and harmony (if there is any), either with the normal piano sound or with instrument patches (such as strings or woodwinds). Once I've finished this initial 'sketch', I'll start arranging the piece (which instruments should play which parts). The basic style and instrument constraints are usually decided before writing any music. For example, with Overgrowth we decided not to use any human choirs since it has no human characters, and I don't have a clue what a choir of singing rabbits would sound like. We also decided not to use brass instruments, because they are more technologically advanced than the societies shown in Overgrowth. As you've heard so far, Overgrowth's orchestrations are heavily based on string sections and woodwinds, as well as percussion-dominated combat tracks.
Some Overgrowth musicians composing a song.
You can hear the strings and woodwinds in ambient tracks like these:
Technology and mastering
From a technical point of view, I first build an instrument setup with sample patches that I'm going to use in orchestrations. This usually means dozens of tracks, requiring a lot of processing power. My Mac running Logic Studio was not up to the task, so I got an additional computer to share the load -- a PC running Gigastudio. String instruments are usually the greediest instruments memory-wise, so most of them are recorded from the PC, and controlled by the Mac via MIDI. Here's a picture of my setup -- you can read my post about it if you're interested in more details:
Mixing a song with 40+ instrument tracks is not the easiest task - it can take more time than the actual composing. Most of the processing power here is consumed by sound processing plug-ins, such as equalization, dynamics, and reverberations. I use these both for single-instrument channels and for grouped instrument sections. The final part of the entire music production process is to set the tone and dynamics in balance between all music tracks to make the sound more coherent. This is a precise and time-consuming task, so I only do this when it's certain that no modifications or new tracks are needed.
Working with game developers
Here's some advice to help you if you're thinking of starting to compose music for games: never polish a track before you first send it to the developers for feedback, because it might get rejected. On the other hand, when a track manages to impress the developers in its rough beta stage, it will surely impress them even more when you send the polished final mix! Of course, if it turns out that a track that sounded great by itself is not working so well in-game, a new track or a modification will be needed - sometimes you need to go through this process several times to get a great in-game track. This Overgrowth theme has had a dozen revisions, even before it was tested in-game!
Testing on different speakers
It's also important to test music tracks with different speaker setups, to make sure that they sound good for everyone. Use all kind of speakers: hi-fi models, amplified ones, laptop speakers, and also the cheapest and crappiest ones you can find - and don't forget different headphones as well! It's not uncommon for gamers to spend $600 on their fancy graphics card, and $50 on their speakers.
I hope this clarified some aspects of what I do for Overgrowth! Do you have any other questions about composing game soundtracks?