City of Beats, and the pursuit of flow state

This is an article about City of Beats, a forthcoming music-driven shooter by Torched Hill, published by Freedom Games.

When we started making City of Beats, our goal was to provide interesting, involving gameplay that could easily induce a state of ‘flow’ in the player. In other words, an experience which truly connects and immerses the participant into the game, by creating feedback systems and balanced gameplay that satisfies the conditions required to occupy the player’s full attention; empowering and rewarding whilst providing just the right amount of challenge.

From working together on experimental concepts, and on our previous game Road to Ballhalla, we both already knew just how powerful a tool music can be in providing effective feedback, when it is utilised in a highly adaptive or interactive fashion. To put it simply- if your actions affect the music, the result is an immediate and emotional response, and the more interactive you make a soundtrack, the greater the sense of connection and involvement in the player. Fans of rhythm-action games know this all too well- it is a genre of gaming that truly entrances players.

But we weren’t particularly interested in making a rhythm-action game. For one thing, mashing buttons in time to music is a pretty limited gameplay mechanic, but it also excludes a large number of gamers who feel they lack a good sense of rhythm or musicality. Our key philosophy is that music should not be the main focus of the game, but instead can be a powerful tool to achieve the immersion and involvement that we want to provide. We wanted to create a world in which all enemy actions and movements are synced and driven by the music, in which everything that happens in the environment is linked to different elements of the soundtrack. And then, to truly connect the player into that environment, to create weapons that effortlessly participate in that music, without requiring anything more than holding down a trigger. To create a sense that your weapons are musical instruments, that automatically contribute to a musical score without requiring any understanding of the music that the player is now a part of.

IncrediblyDaman playing a very early pre-alpha build of the game

To achieve this, we constructed a system utilising fMod, a 3rd party audio engine, using a large number of interchangeable and procedurally triggered core background tracks, on top of which all the other musical systems operate in a context sensitive fashion. The rhythms of enemy movements, and the timing of their weapons is generated by triggers within those core tracks, with bass drum patterns dictating movements and snare drum patterns defining the attacks. Becoming familiar with the music therefore gives the player an advantage, being able to predict actions and hazards, without having to consciously think about them. Additionally, enemies all have individual musical motifs which help the player prepare accordingly (e.g. snipers emit a buildup motif before they fire), and alerts the player as to what types of enemy are still active at that point.

Building upon that, we introduced sets of melodic sounds that change according to the harmony of the background track. These are used as reward mechanics, providing satisfying chords and notes in the appropriate key to signal positive events such as the destruction of enemies, or the action of picking up health orbs, and the timing is quantised so that they sound on the nearest beat, resulting in a seamless addition to the rest of the soundtrack.

But the most powerful aspect of our system has to be those melodious weapons: a repeater that shoots notes at a steady rate on every quarter beat; a lightning bow that shoots at a slower pace but triggers additional notes on quarter beats when that electricity chains onto other nearby enemies; and a flamethrower that introduces a layer of pure harmonic euphoria. These melodies are all pre-written to fit the background harmonies and are coded as individual notes that sound or do not sound depending on whether the trigger is being held down. Each weapon has a secondary function which further contributes to the melody, and by alternating triggers the player can feel involved in the soundtrack in a very natural and effortless way.

There have been many challenges in making everything work fluently, and providing the right balance between familiarity and repetitiveness. And while we think it was been worthwhile for the reasons I’ve mentioned above, watching players’ reactions as they pull the trigger for the first time reminds us the most important benefit of all: It just feels good.

For a more technical look at the techniques we used, check out my pinned twitter threads here and here.