Spooky Oni Mansion Tunes

Yomi Games
4 min readApr 13, 2022


The Oni Mansion NFTs are custom-designed by playing the Oni Mansion game. Players earned Oni mansion coins to buy decorations and won loot boxes. Every single one of the 343 Oni mansion NFTs comes with a spooky melody, setting the scene for the Oni mansion game. Each tune unique to every Oni Mansion NFT was composed and algorithmically generated by Michael and Vova from MusicJotter.

The music drew key influences from Danny Elfman (Nightmare Before Christmas and Edward Scissorhands) and John Williams (who scored for top films including Star Wars and Harry Potter). Another source of inspiration came from the whimsical beats of Magical Mystery Tour by The Beatles; video game soundtracks from Super Mario 3d, Plants vs. Zombies, and Castlevania added a playful spin to reflect the friendliness of the Onis.

The composition strived for variety, and to avoid a monotonous song, several different instruments combined with synthesizers gave it more traditional orchestral harmonies. To further spice up the mood, a Ukrainian instrument, the bandura, was added, along with guitars, drum sets, etc., to give the melodies more variety! The theremin was heavily incorporated into the music to deliver a creepy atmosphere.

Being lovers of instrumental music, they began by experimenting on the piano to create 140 12-second melody snippets that could be stitched together to generate 300+ songs.

Take a look at the metadata of the Oni Mansion NFTs on Opensea, and you can see three sections of music; each song clip is labeled Music 1,2, and 3. The key to generative music is to create themes that connect well together. To sound natural, they have to conform to specific rules:

  • Maintain the same key signature (In this case, A Minor was used)
  • Time signature to manage the length of the piece
  • Each motif overlays to smooth the transition
  • Added reverb to add realism

Combining the clips was a linear process; each piece is composed of a series of Motifs- a jingle. A total of 140 motifs were created to produce enough variations to avoid similarity and monotony.

Each motif has 5 openings, 5 bodies, and 5 fillers — totaling 15 pieces per motif:

  1. Opening is how each motif starts
  2. The body is in the middle of the piece
  3. Filler helps to provide random variation

The composers integrated a series of motifs to create a Theme, and at the very top level, we selected a Halloween theme for the Oni Mansion music, the Genre, to set the scene.

However, merging the motifs also came with challenges. MusicJotter developed an API and formula to determine which point the next motif conjoins with the previous piece, accounting for the reverb to sound natural. Slight variations were made to the key signature while maintaining its likeliness to A minor helped add more assortment without introducing a jarring transition. MusicJotter’s script randomized the motifs to create unique tunes. Finally, a total of around 800 pieces were generated and then applied with the API to mix them all within the Halloween theme.

Nothing can beat the human mind. Combining human creativity with technology to generate the music randomly allowed seamless mixing and matching. We are thrilled and spooked with the final production of the music, and I hope you enjoy these eerie tunes too!


Oni Mansion on OpenSea



Yomi Games

Gaming studio developing casual mobile games featuring digital collectibles. Our next titles include Yomi Block Puzzle, Yomi Gardens, and more coming soon!