Exploring Killer Instinct's next-gen audio

At this year's GDC, Killer Instinct composer Mick Gordon and Double Helix sound designer Jean-Edouard Miclot gave a presentation breaking down how the game used the increased headroom of the Xbox One hardware to re-imagine one of the original Killer Instinct's most distinctive aspects.

Miclot began by explaining that 90s arcades necessitated a certain kind of sound and volume for a game to stand out of the crowd. The original Killer Instinct was one of these so-called "loud" games, the cabinet practically shaking from in-game sound effects and its infamous announcer. According to Gordon, this high-volume, subwoofer-rattling sound scheme "lured over the punters," along with what original developer Rare dubbed at the time "modern sound." Rare's approach was to make Killer Instinct sound like something you'd see on television or in theaters, with an at-the-time unprecedented amount of digitally captured music and voice.

This created a dilemma for Killer Instinct 2013's developer Double Helix when they were handed the series in 2012 with the goal of making the Xbox One's launch. Their approach took inspiration from car design over the last fifty years —every model has a specific look and set of design concepts that sees changes and additions over time while retaining what Gordon called its "brand essence."

Figuring out what Killer Instinct's brand essence was started, perhaps unsurprisingly, with its series-defining announcer. Originally voiced by Rare producer Chris Sutherland — who's still with the UK-based developer — Double Helix thought to re-record him and be done with it. But after 17 years, Sutherland's voice had changed enough to cause difficulties. To assist with recapturing the essence of the original, Rare sent DAT recordings from the original Killer Instinct's voiceover to Double Helix, which were then re-processed for the 2013 release.

Miclot talked about building the audio identity of the game and its characters, explaining that he recorded 1,700 audio takes, starting in Double Helix's kitchen. These were then processed in ProTools using various plugins, and categorized for low, medium and heavy attacks.

Each character also has a melodic theme behind some of their character-specific aspects. Miclot used cougar sounds with echo applied for Orchid's special moves, for example, and her standard attacks have processed elements lifted from tesla coils and steam off of oven burners (from the aforementioned Double Helix kitchen). Sadira used female whispers for her background ambiance, while her web-based attacks are based on pitch-shifted sounds of duct tape being stretched and pulled. Miclot went on to explain the challenges of designing the vocalizations of a character without a mouth, referring to the alien Glacius. He eventually settled on the sounds of water injecting into a steam iron for the alien's breath, and the horn-like noises he emits come from pitch-shifted and altered rubber bands strummed in front of a condenser mic.

The second half of the panel was dedicated to Killer Instinct's unique soundtrack system. Gordon explained his philosophy for the game: "Music is storytelling," as he put it. As each match has a narrative structure -— two characters enter, the round begins, each player trades blows, ending with a knockout — it was important that the game be able to pick the right moments to shift music and add or subtract elements to add momentum and drama to each fight.

Gordon's solution was to treat each song in the game as a pop composition with a verse, bridge and chorus that players control, whether they know it or not. As each fight begins, the first player's entrance theme plays. When the second player enters, their theme is added to the audio mix, with a specific beat matched to that character jumping down into the arena. When the round starts, the "verse" begins — actually a combination of several tracks playing simultaneously in slightly different ways to match the action on screen, mixing interludes, "part As," "part Bs," riffs and more. Essentially, players will never hear a verse the exact same way twice.

But Killer Instinct's audio hinges in particular around Gordon's chorus system. When a player lands a 15 hit or more combo, the verse uses a strategically triggered kick drum to transition to the first eight bars of the song's chorus. If a player lands another 15 hit combo within those eight bars, the next eight bars of the chorus trigger, and so on, and the chorus' intensity builds as it goes on. If neither player successfully achieves a strong enough combo, the verse fades back in. Super bars add additional complexity to Killer Instinct's sound field; when a player's bar is full, it plays an additional theme in the speaker corresponding to their side of the screen.

You can hear one of Killer Instinct's choruses kick in around the 40 second mark.

Gordon closed the talk with an explanation of the melodic system behind Killer Instinct's ultra combos, which smash out a unique melody for each character at the end of a match — assuming a player pulls them off correctly. Gordon revealed that the original inspiration for this system came from last fall's Rayman Legends and its musical levels, where music is accompanied by perfectly timed visual cues.

To make something similar work in Killer Instinct, each level was broken into 50 "hits," an escalating set of musical scales. Each character has a sequences of moves that land on certain hits, which the game selects based on specific punches or kicks. This creates a unique "ultra" melody for every character on every level.

In response to an audience question, both Miclot and Gordon stressed that the Xbox One's increase in hardware capability over the Xbox 360 didn't eliminate restrictions or limitations. Instead, they said, it forced the studio to decide what their restrictions would be, rather than having them dictated by eight year old hardware.