Ultros’ composer Oscar Rydelius traveled to ‘the lungs of the world’ just to record audio for the upcoming metroidvania

Character falling from the sky in front of another character
(Image credit: Kepler Interactive)

Ultros has no problem standing out from the metroidvania crowd. Its vibrant colors and detailed psychedelic art style mean that it's a joy to simply look at. However, some of the 2D platformer’s most outstanding achievements cannot be seen; listen closely, and you’ll discover even more about the game.

Ahead of Ultros’ launch on February 13, TechRadar Gaming (TRG) got to sit down with the composer Oscar Rydelius and discuss what lengths the team at Hadoque went to so they could achieve the incredible audio - and why this was so important. 

As part of the research and development of Ultros, Rydelius traveled to Peru to record audio and music, which would later be used in the 2D platformer. While this may seem like a long way to go for some background audio, it was necessary to achieve the right kind of environmental and hypernatural atmosphere in Ultros

“Peru was obviously an inspiration to both me and Niklas Åkerblad, (our artist on Ultros),” Rydelius explains. “Sweden has a lot of forests and nature, but our connection is kind of weird and stunted. But what I experienced in Peru is completely different. They have this idea of Pachamama, who is like Mother Earth, and it feels like everyone there has some sort of connection with this being.”

To nature’s heart 

Statues worshiping a green light

(Image credit: Kepler Interactive)

Rydelius’ travels saw him venture across Peru, visiting famous historical sites like Machu Pichu as well as traveling along the Amazon River by boat, all in the name of sound design. “I remember going on the Amazon River,” Rydelius recalls.”You couldn’t have been further from the city. I felt like crying and had endless goosebumps being in the lungs of the world.” 

During his time in the Amazon, Rydelius was able to capture various incredible recordings of birds and other wildlife unique to that habitat. “I brought with me this special microphone that records up to 96,000 Hertz (Hz),” Rydelius recalls. “Humans can only hear to 44,000Hz, so we were able to record sounds above our hearing. After this, we manipulated and pitched down the audio.” This technique is one of the many reasons why Ultros’ audio sounds so unique, and with any other microphone, these ethereal noises may have been lost.

I met so many young people who were on a wave of reclaiming this culture

Oscar Rydelius

However, the noises of the Amazon weren’t the only sounds that Rydelius recorded while he was in Peru. From the beginning, he set out with the goal of finding Peruvian Whistling Vessels. These are one- or two-chambered vessels that can emulate various animal or bird calls by either blowing into the spout or tipping liquid from one chamber to another. 

“It's mimicking everything from birds to wolves and all kinds of other different things,” Rydelius explains. “So obviously, that was also one of the reasons why I wanted to go. I went on some tours and met some people and then finally fixed studio session recordings where we recorded all of these historical instruments.” 

Rydelius’ travels across Peru also brought him face-to-face with the impressive yet horrifying Death Whistle. These were instruments that historians believed indigenous people thought would guide spirits to the afterlife or scare enemies during battle. The latter is entirely possible as the sound that emanates from these objects can be likened to a blood-curdling scream and would scare even the bravest among us. “It was amazing to encounter this tool. I get goosebumps talking about it,” Rydelius says. Luckily for players, the noise of this whistle isn’t predominant in Ultros

But Rydelius wasn’t just impressed with the sounds of Peru. “The culture was incredible,” Rydelius says. “I met so many young people who were on a wave of reclaiming this culture that I was interested in, going back to what it once was. If I can be any part of promoting that in any way, I will be super happy.”

Coming together 

Character planting and watching a tree grow

(Image credit: Kepler Interactive)

canManipulating the various sounds was also integral to creating what many will soon find to be an otherworldly experience. All of these instruments, animal calls, and noises from the undergrowth come together in Ultros’ stunning audio track, which helps the player feel like they’re walking into the heart of Mother Nature herself. 

“Even after manipulating the audio, I feel like people would still know where the noises are from, but then they would also sound a bit outlandish, alien-like,” Rydelius explains. “There was a lot of experimentation and work to try to find that perfect balance of familiarity and the unknown.” 

As you venture across the psychedelic landscape of Ultros, passing through untamed wilderness and artifacts of a forgotten past, you can hear the distorted sounds of bird calls between the drawn-out string chords. However, when you encounter an untamed beast, the tranquil bird songs often escalate into angelic and fast-paced orchestral music, a fantastic way to distinguish between exploration and action.

Overall, it’s clear that Rydelius’ time in Peru was well spent. The stunning soundtrack, which I’m sure will captivate players once they dive into Ultros when the game launches this month, is an unforgettable and uniquely beautiful experience. 

For more incredible games with amazing soundtracks, be sure to check out the best story games as well as the best indie games that are available to play right now.

Elie Gould
Features Writer

Elie is a Features Writer for TechRadar Gaming, here to write about anything new or slightly weird. Before writing for TRG, Elie studied for a Masters at Cardiff University JOMEC in International Journalism and Documentaries – spending their free time filming short docs or editing the gaming section for their student publications. 


Elie’s first step into gaming was through Pokémon but they've taken the natural next step in the horror genre. Any and every game that would keep you up at night is on their list to play - despite the fact that one of Elie’s biggest fears is being chased.