When I play a game, one of the first things I pay close attention to is its music. A game is like an interactive hybrid of storybook and movie, telling you a story while letting you into its world. If a game is to entrap you in its plot's conflict and make you feel pathos for its characters, its soundtrack is key. And nothing says climax and conflict like an orchestrated or cleverly arranged soundtrack bearing the natural sounds of musical instruments.
Of course, each game is unique, and if you included live orchestrated music in every game, for example, things would get boring and stale and would sound too much like a Renaissance game. But if you include just a few of these music tracks at correct times, a game can truly become an adventure. For example, if you listen to one of the many battle themes from Shadow of the Colossus, the word "epic" comes to mind.
Epic tales and poetry predominantly tell the story of a hero on a perilous quest for something grand. Readers follow this hero on his risky and bold adventures as he fends off horrible monsters and avoids traps that try to prevent him from going home. Along the way, he grows wiser and more mature and learns about himself and human nature. I think this adjective is appropriate to this type of music. Don't you?
For those of you who played Shadow of the Colossus and remember fighting each colossus, the music made a great impact on how you felt during these fights. When you first encounter a colossus, the music that begins playing is calm and alluring. This creates a feeling of confusion and it mimics the player's thought process. "What do I do now?" Then, as you finally find a way onto the giant and find its weak spot, the music picks up speed and a new music track is heard that amplifies the first. This track is full of cymbals, drums, and horns that turn this seemingly mundane encounter into an epic test of endurance to hang on tight and to defeat the beast. A struggle of David vs. Goliath.
Orchestrated music like this gives players a feeling or urgency and a rush of adrenaline. Having moments where music changes during a boss battle gives games a whole new depth and layer of motion. The Legend of Zelda Twilight Princess did this as well. It didn't include a full live orchestrated soundtrack, but the sudden change in musical speed and rhythm made boss battles awesome. As soon as you find a boss's weakness, the song changes to inform you and Link that an opening has been made and it is time to hurry. Metal Gear Solid: Guns of the Patriots showcase this urgency too thanks to its theme song's violins pulling at your heart strings and its snare drums leading you to war.
Other games choose to have orchestrated music incorporated throughout the entire game beyond boss battles. Final Fantasy games are known for having music like this. In fact, it's usually RPG games or action RPG games that incorporate music in a style that gives the game a new level of enjoyment. In an RPG's case, an orchestra can take a player back in time to an age where technology did not exist and where villages and historical domiciles scatter the land as seen in the Dragon Quest and Fable series. Hence by this method, this type of music can create a time-line for the player.
Various countries have their own unique musical instruments that, when used in music, easily associates it to that country's culture and people. The globe-spanning fighting game Soul Calibur III, for example, gives each of its characters a unique theme song that includes instruments from their respective countries such as the Chinese fiddle, the Japanese koto, and the uilleann pipes. Its sequel, Soul Calibur IV, gives each of its ethnically-varied stages its own distinct theme filled with traditional instruments as well.
It is also important to note that by incorporating a choir or a vocal hymn into any song, battles and encounters become something more human and perhaps even more holy, greatly elevating the importance of winning for fear of the consequence of defeat. When Mario has to fight Bowser at the end of Super Mario Galaxy 2, the choir kicks in signifying the climax of the battle and the imminent struggle for universal dominance. It is also safe to say One Winged Angel is a quintessential example of this type of holy struggle for power.
Today's modern games also use orchestrated music to mimic a live action film's sense of action and storytelling. When playing Uncharted 2: Among Thieves, you'll not only uncover mysteries in Tibet alongside whimsical pipe flutes, but you'll also have to escape the rush of drums while snipers target your head. The eerie theme of Ezio's Family in Assassins Creed II can give you a back-story on a character who is a more complex than meets the eye. These kinds of themes are audible context clues that accompany a character's story taking you along for the ride.
Regardless of how it's used, well created music has the power to make a game truly an adventure. Remember how Super Smash Bros. Melee turned a seemingly humble Pokémon theme song into a grand symphony complete with a choir for the Pokémon Stadium stage? Or what about a little pink puffball's epic clash of cymbals in Fountain of Dreams?