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Game Module: kbm

This mode will be added around alpha 4.19.0/alpha 5.0.0-pre45-ish of Project OutFox.


This mode parses files made in the bmson format, and usually is arranged into a two octave keyboard layout, sporting 24 keys in a piano style layout. This mode also supports 4 octave mode, or 48 keys. It is Highly recommended that this mode is played on a MIDI controller, or if you can find one, an original keyboardmania Playstation 2 controller from the early 2000s


The parser support for the mode (bmson) is currently in development as it requires a new parser system to be initialised and set up for this type of chart.

This mode is not selectable in the game select screen at the moment.


24 Key 2 Octave:

kbm24 layout

First Seen:

  • Project OutFox alpha 4.18.0 - (kbm24-single) (November 2022)
  • Project OutFox alpha 4.18.0 - (kbm24-versus) (November 2022)

48 Key 4 Octave:

kbm48 layout

First Seen:

  • Project OutFox alpha 4.18.0 - (kbm48-single) (November 2022)

Supported Parser Types:

This mode is parser specific. It will only load and parse items designed for the BeMusic Script JSON (bmson).

The table below lists the supported files and their types that kbm supports, their key/button value and the original mode the parser is used for (if any).

File Type Label Original Mode Key Values Supported Notes
.bmson BMSON kbm 24k / 48k 2 Octave / 4 Octave kbm charts

Game play

This mode is played default in down scroll, with the note receptors at the bottom of the screen. The player then hits the piano notes depending on how they fall.


key sounded

The notes in this mode are based off of small clips of audio that react when you press a key. This means buttons you press will add to the song being played. Similarly there can be percussion and other sound effects added to these. Due to the nature of key sounded charts, they take longer to load and compile than other charts, so do not be surprised if you see a ’loading screen’ for be-mu charts!

Play Styles

Grading / Accuracy


Health Bar

The “health bar” in this mode is called a ‘gauge’. It is a measure of accuracy as well as your ’life’. Depending on the difficulty you need to achieve a specific percentage to pass a song.




The game is played best on a MIDI piano or mini-keyboard controller.

The original PSX/PS2 era controllers can be unusually difficult to use, so be mindful if they stick or are a bit stiff, they likely need a good service and clean.


bmson is based on a rewrite of the BMS format, but with an attempt to make it easier to make/parse for creators.

Written and Maintained with ♡ by Squirrel