Best practices

In order for your mod to be approved as soon as possible, you must ensure that it complies with all requirements so it can be playable on all devices and platforms.

As game designers do, you have to optimize all your mod's assets. Always find the right balance between file size and file quality. Keep in mind that every kilobyte saved counts for your mod to run smoothly, even on small or low-performance devices, so all users could enjoy it.

We advise you to stay focus on your HD assets during the entire building process, then to manage LD files compliance at the end. LD files (low definition) are just HD files with a half resolution, so for a good start just remove all -ld files from your mod folder.

The Modbox

The Modbox is a folder containing a mod example based on V4 assets plus useful source files. Organize your own assets based on this specific file structure. Import and try the modbox from the settings pannel of the Incredibox app so you can see exactly how your mod will look for users.

By downloading the modbox, I acknowledge I have read, understood and accepted the Incredibox GTU.

App.json

modbox/app.json

You have to edit the app.json file to change information about the mod such as title, modder credits, loop duration, number of animations, bonuses, path to files, etc. Example below:

{
    "name": "Modbox",			// Your mod name
    "date": "2025-05-19",		// Mod creation date "year-month-day"
    "looptime": 8000,			// Sound loop duration in milliseconds
    "bpm": 120,				// Rhythm (Beats Per Minute) of the music [only for info]
    "totalframe": 384,			// How many frames per animation (in principle: looptime x 2 x 24ips)
    "bonusloopA": true,			// true if bonus can only start on loopA and not on loopB (depends on your musical composition)
    "bonusendloopA": false,		// true if you want to force the metronome to restart a loopA after a bonus has finished when it should in principle have been a loopB (really rare)
    "colors":["#D8A365", ...],		// 6 hex colors gradient based on your mod's main hue (see home-screen.ai in the modbox and ensure proper UI readability in the app)
    "animearray": [			// List of sound/animation files (max 20)
        {
            "name":"drum1_kick",	// name of the animation/sound file (without extension) stored in both the anime/ and sound/ folders
            "color":"#E5A90E",		// hexadecimal pictogram color
            "uniqsnd":false 		// true if sound composed with only one loop, false if composed with 2 loops (A and B)
        },
        { ... }
    ],
    "bonusarray": [			// List of bonuses (max 3) "bonusarray" can be removed if you don't have bonuses
        {
            "title": "Love",		// Title of the bonus [only for info]
            "code": [1,2,6,11,17],	// Array of 5 picto ids to unlock the bonus
            "name": "b1-love",		// File name of the mp4 video file (without extension) stored in the bonus/ folder
            "sound": "bonus1_love",	// File name of the bonus sound (without extension) stored in the sound/ folder
            "predrop": "bonus_predrop",	// File name if a sound should play before the bonus launch
            "loop": 1			// How many loops the bonus lasts
        },
        { ... }
    ],
    "credit":{				// Modder info
        "crewname": "ARP modders",	// Modder crew name
        "process":["Allan", "Romain"],	// Roles of modders (names needs to be separated by double-quotes and commas so users can search for a specific modder's name using the search form)
        "music":["Paul"],		// Just remove a "role" if not needed
        "design":["Romain"],
        "animation":["Allan"],
        "thanks": "To the best community ever"
    }
}

Image

modbox/image/

You can replace files within the image/ folder with your own (mod icon, home screen, picto, etc.). We provide you with some original source files (Adobe Illustrator) so you can better understand how to make them. Take care to respect the object position in the page, image size exported, extension file and file names (images in this folder need to keep their original name and their original size/resolution).

Sound

modbox/sound/

You can use any music editing software to record, edit and export your sound loops (only MP3 files are accepted). Replace the files in the sound/ folder with your own. The names of your audio files must match the key/value name in animearray from app.json (names of audio files and animation sprites are the same).

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Loops mechanism

• All loops have the same duration (neither too short nor too long, do something consistent for the user experience).
• The duration of your loops must be set using the looptime key/value from app.json.
• Incredibox’s music engine launches a looping metronome based on the looptime duration.
• Each time the metronome does a loop (each bar), it switches between 2 states: loopA, loopB, loopA, loopB, etc. This allows for more variations within the musical composition. For example, you can have a basic beat with a binary rhythm during loopA (first bar), making a small change during loopB (second bar). This means that, if your sound never changes from loopA to B, include only one sound file in the folder (uniqsnd: true in app.json). Otherwise, include 2 sounds with stateA and stateB. Analyze the following diagram: during loopB, the metronome will play stateB of a sound if it exists: otherwise, it will play stateA.

|1		|2		|3		|4		|5		| ... |
|loopA		|loopB		|loopA		|loopB		|loopA		| ... |
|beat_stateA	|beat_stateB	|beat_stateA	|beat_stateB	|beat_stateA	| ... |
|voice_stateA	|voice_stateA	|voice_stateA	|voice_stateA	|voice_stateA	| ... |

sound/mp3/beat_a.mp3
sound/mp3/beat_b.mp3
sound/mp3/voice_a.mp3

---

Bonus music mechanism

• The audio duration of your bonus must be a multiple (x1, x2, x3, x4, etc) of your sound loops.
• The bonus can be launched in loopA or both A and B (see bonusloopA in app.json).
• You can launch a sound called predrop during the loop before the bonus starts (see predrop in bonusarray from app.json).
• Example with a 2-loop bonus which must start at loopA with a predrop sound.

|1		|2		|3		|4		|5		| ... |
|loopA		|loopB		|loopA		|loopB		|loopA		| ... |
|beat_stateA	|beat_stateB	|		|		|beat_stateA	| ... |
|voice_stateA	|voice_stateA	|		|		|voice_stateA	| ... |
|		|predrop	|bonus_playing	|bonus_playing	|		| ... |

sound/mp3/beat_a.mp3
sound/mp3/beat_b.mp3
sound/mp3/voice_a.mp3
sound/mp3/bonus.mp3
sound/mp3/bonus-predrop.mp3

---

Audio optimization

Once all your sounds loop are 100% finished, you have to export it as MP3 files (best format so your mod can be cross-platform and playable on any devices by users). To provide users with the best audio experience, make sure each combination sounds good to your ears and be very careful never to touch saturation in the stereo output of your DAW before exporting. As music producers do, always take care of having the lowest file size possible by losing audio quality until a non perceptible level. For example if you check audio files we provide in the modbox, you will see MP3 files size around 50 and 100 Ko.

Bonus

modbox/bonus/

You can use any video software to make your video (we recommend using Adobe Animate). Replace files in the bonus/ folder with your own. Your video must be 1920x768px, in MP4 format only. Your video must not include any audio tracks.

• You can include up to 3 videos in your mod (if 0, just remove bonusarray in app.json).
• The duration of your video must be a multiple (x1, x2, x3, x4, etc) of your sound loops.
• Bonuses can have different lengths (see loop in bonusarray).
• The names of your video files must match the key/value name in bonusarray.
• Beside your MP4 video file, put an SVG file (70x70px) with the same name.

---

Video optimization

Once all your videos are 100% finished, you have to export them as MP4 files. As video producers do, always take care of having the lowest video file size by loosing details and quality until an acceptable level. For example if you check video files we provide in the modbox, you will see MP4 files size around 500 Ko (of course it depends the video duration and graphism complexity, videos from Dystopia which are longer are around 5 and 8 Mo).

We recommend Handbrake for video compression. This software reduce mp4 file size and let you export a half size version (LD format) from your HD video.

Anime

modbox/anime/

In this folder, you have to organize your animated character files (aka the polos). The Incredibox graphics engine works with a homemade mechanism. You have to use Adobe Animate to open and edit our .fla source file. It will let you save so much time on lipsync and you'll never again have to edit every sprite.json file manually 😅

• You can include a maximum of 20 polos in your mod (same number as your loops and pictos).
• SWF file size must be 164x380px (will be 328x760px once exported as a PNG sprite).
• Prefer vector assets within the SWF so you don't have to worry about resolution.
• The names of your animation files must match the key/value name in animearray.
• Convert your SWF to a PNG sprite with our SWF2sprite tool.

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Custom polo sprite

You can customize the waiting polo on the stage by editing the .ai source file provided in the anime folder. Edit and export your own 0_polo.png sprite to overwrite the default one.

modbox/anime/0_polo.png (1312x960px)
HD sprite of the waiting polo on the stage.

modbox/anime/0_polo-ld.png (656x480px)
LD sprite of the waiting polo on the stage.

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Make animation

Open and edit the polo-template.fla with Adobe Animate. The specific tree structure and object names in this file are required for the final exportation steps (SWF to PNG sprite). You just have to hit CTRL+ENTER to export and run the SWF file of your animation. Keep this file structure and organization:

file.fla
└── stage
    └── polo
        ├── headanim
        │   └── limit
        ├── headwait
        └── costume

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Convert animation to sprite (SWF2Sprite)

Once your animation looks great, you can convert your SWF into a PNG sprite file. Open our SWF2sprite tool (you need an SWF reader such as Adobe Flash/Animate installed on your computer) and click Convert to select your SWF animation file. If you've respected the file tree structure and object names from the polo-template.fla, you should see the SWF2sprite analyzing your animation. It will compare each face to save only different ones before exporting a PNG file (try not exceed more than 40 faces per sprite). Plus, the tool will generate and export a JSON file filled with all data needed by the Incredibox graphics engine (such as polo's head xy position, head height, crop size, etc.).

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Include animation

Once you have exported your animation PNG sprite and JSON data, you can put this files into the anime/ folder. Don't forget to add your animation name by editing the key/value name of the animearray array in the app.json file (which is also the name of your MP3 audio loops). Import your mod folder into the Incredibox app to check your animation.

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Sprites optimization

To ensure your mod can be playbale on low-performance devices, each of your animation sprites has to come with a LD version (low definition). If the HD PNG file is 2000px width, the LD should be 1000px. Then, just add -ld at the end of the LD file.

modbox/anime/0_polo.png
modbox/anime/0_polo-ld.png
modbox/anime/beat.png
modbox/anime/beat-ld.png
modbox/anime/voice.png
modbox/anime/voice-ld.png
etc.

Warning: depeding on your sprites complexity (more than 40 polos' faces) some low-performance devices starts to run really slowly. This is why image optimization is important, save as much kilobyte as you can by finding the right balance between image quality and file size.