Chapter 15: A DirectMusic Case Study for Russian Squares for Windows XP Plus Pack

Download CD Content

Guy Whitmore

Introduction and Overview

Russian Squares is a puzzle game involving rows and columns of squares. The player eliminates rows of squares by matching the square's color or shape. The game's difficulty increases as the player eliminates the rows of squares; the time given decreases and "blockers" are introduced to get in the player's way. It sounds simple enough, but the game is both challenging and extremely addictive!

The adaptive audio design of Russian Squares offers a wonderful opportunity to demonstrate how an adaptive score works seamlessly with core game design elements. When creating a musical score for a game, start by determining what the game calls for. I approach each game without any particular adaptive technique in mind and brainstorm in the abstract. This way, creative ideas lead to technical decisions. Once I have an abstract idea of how the score will work, the engineering team and I figure out how to execute the adaptive music system with the game engine. I believe that an adaptive audio design document, which should complement or even be a part of the game design document, is an important step in creating a highly adaptive score.

Adaptive Elements

The adaptive elements of a game determine the form of an adaptive score. An important first step is identifying potential adaptive elements that tie gameplay to the music. Start by asking questions about the gameplay. What is the core gameplay element? How does it function? What are secondary gameplay elements? In what ways can I link the music to this gameplay?

Music Cells

The core gameplay of Russian Squares is the elimination and addition of rows of squares. We made this game design element the core of the music functionality. As the game adds rows or the player eliminates them, the music responds with a subtle change; the adaptive music system adds or subtracts an instrument, the harmony or rhythm changes, etc. The music follows the overall pace of the player. To accomplish this, there are about 50 music cells per composition, which correlate to different groove levels. As the player completes rows, the music incrementally transitions to the next groove level. Logical transition boundaries make those transitions musical and seamless. I used mainly measure boundaries for transitions in Russian Squares.

I used music intros, ends, and breaks to kick off and end gameplay. The music transitions to an ambient break section when the player pauses the game. The adaptive music system plays the appropriate intros and ends based on the current music cell.

Variation

Russian Squares uses instrument-level variation to keep the individual cells from getting monotonous. Each groove level is anywhere from two to eight measures in length and repeats as the player works on a given row. Within DirectMusic, each instrument can have up to 32 variations. When combined with other instruments, these variations increase the amount of variation logarithmically. Most often, one to three instruments per cell use variation, and that gives the music an organic, spontaneous feel and prevents that all-too-familiar loopy feeling. Too much variation, however, can unglue the music's cohesion.

Music Layers

Layering short musical gestures over the currently playing groove level accents many gameplay elements, such as the game clock, the clearing and adding of rows, and blockers. I use DirectMusic motifs and secondary Segments to accomplish this. These elements line up rhythmically with the music (i.e., the tempo of the clocks synchronizes with quarter note values of the music).

Sounds

DLS-2 banks allowed for maximum flexibility and variation in this project. Some of the instrument variations control instrument filters (i.e., low pass filter sweeps) in addition to notes, which are crucial for the genre of music. The sounds used are a combination of Sonic Implants (www.sonicimplants.com) and custom banks.

Cooperative Composing

Three other composers (Erik Aho, Mike Min, and Bryan Robbins) assisted in creating the three arrangements. Working with nonlinear cells made it easy to work simultaneously. Generally, we assigned a range of cells to each composer. Often, someone would start an idea and the next composer would elaborate on it or add variations. This method of working made sharing musical ideas easy and kept everything musically coherent.