The first video games to include music were limited to a basic melody and accompaniment. In the earliest games, sounds were limited to basic electronic sounds triggered by simple synthesisers. The length and quality of sounds included in games were limited by the tiny memory capacity of early computers.
Sound effects play a vital role in a game’s overall soundtrack. The classic game Space Invaders has only sound effects, each sound being a reaction to what happens in the game.
As gaming technology developed, more memory space was available for bigger music files. The technology opened the door to new sounds that were less synthetic and more like naturally sounding instruments. Another technology, sampling, began to be used for the soundtrack of video games, which made it possible to include realistic sound effects and instrumental sounds too.
The game Hitman - produced in 2000 - featured the first fully-orchestrated soundtrack. The sound of a real string section creates an eerie timbre, coupled with a descending melodic pattern, leaving an ominous sense of tension.
Video game music is an now at a point when composers are favouring the sound of a live orchestra over synthesised technology. Composers have to be able to manipulate ideas to represent a wide range of emotions and locations that the player might find themselves in within a game. Themes, similar to a leitmotif that you might hear in films, are used countless times within a game to represent characters, specific locations, emotions and other core components of the game.