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A frontend for the SameBoy GameBoy emulator, with a focus on music creation. It runs standalone and can be used as an audio plugin (VST) in your favourite DAW!



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A frontend for the SameBoy GameBoy emulator, with a focus on music creation. It runs standalone and can be used as an audio plugin (VST) in your favourite DAW!


  • Wraps SameBoy v0.15.7
  • Full MIDI support for mGB
  • Syncs LSDj to your DAW
  • Emulates various Arduinoboy modes
  • LSDj tooling - Realtime sample patching, .sav manipulation
  • Lua scripting


Visit the releases page to download the latest version.


  • Standalone:
    • Currently the standalone build is provided as a single executable file that can be placed anywhere you'd like.
  • VST (Windows):
    • Place the plugin .dll in your VST search path. These paths can generally be configured in your DAW, though the following tend to be the recommended defaults:
      • VST2 (Windows): C:\Program Files\Common Files\VST2

NOTE: Depending on your system configuration, you may need to install the latest Visual C++ redistributable from Microsoft. If the plugin crashes when you try to load it, this is most likely the cause.


  • Double click to open file browser, or drag a rom on to the UI to load
  • A .sav with the same name as your rom will be loaded if it is present
  • Right click to bring up a menu with various options
  • The emulator state is saved in to the project file in your DAW when you hit save, which will persist your changes. YOUR .sav IS NOT AUTO SAVED. If you want to save out the .sav then do so from the SRAM context menu.
  • For mGB, the usual Arduinoboy rules apply: - no additional config needed, just throw notes at it!
  • For LSDj, an additional menu will appear in the settings menu, allowing you to set sync modes (Arduinoboy emulation)


RetroPlug is configurable with Lua configuration files. The configuration files are written on first load if they do not exist, and will be written to the following locations:

  • Windows: C:\Users\USERNAME\AppData\Roaming\RetroPlug

You can get to this folder quickly by using the Settings -> Open Settings Folder... option in the context menu.

  • config.lua - contains default options for projects and systems
  • input/*.lua - contains various input configurations

Button Mapping

The following are defined as the default keyboard and joypad mappings:

Button Default key Default pad button
Up UpArrow Up, Left Analog Up
Down DownArrow Down, Left Analog Down
Left LeftArrow Left, Left Analog Left
Right RightArrow Right, Left Analog Right
Select Ctrl Select (+ R2 for LSDj)
Start Enter Start

There are also LSDj specific key bindings to actions:

Action Default key Default pad button
DownTenRows PageDown R1
UpTenRows PageUp L1
CancelSelection Esc N/A
Delete Delete N/A
StartSelection Shift (Hold) X
CopySelection Ctrl + C N/A
CutSelection Ctrl + X N/A
PasteSelection Ctrl + V N/A
ScreenUp N/A Right Analog Up
ScreenDown N/A Right Analog Down
ScreenLeft N/A Right Analog Left
ScreenRight N/A Right Analog Right

Additionally, Tab / Pad Y can be used to move between instances when multiple systems are loaded, and Ctrl + S can be used to save your project.

Modifying Button Maps

Input maps have their own specific configuration format. Both keyboard and pad inputs can be assigned directly to Gameboy buttons, or they can be assigned to actions which are defined in Lua scripts. Both keyboard and pad inputs can be defined in a single file, but can be chosen independently of each other in a project.

To modify the button mapping, you can either edit one of the currently existing button maps, or create your own. It is recommended that you make a copy of input/default.lua and modify it to suit your needs. Your button map can then be selected in the context menu via the Settings -> Keyboard and Settings -> Pad menu options.

Supported Keys:

Keys 0 - 9 and A - Z can be used for alpha numeric keys, as well as the following keys:

Backspace, Tab, Clear, Enter, Shift, Ctrl, Alt, Pause, Caps, Esc, Space, PageUp, PageDown, End, Home, LeftArrow, UpArrow, RightArrow, DownArrow, Select, Print, Execute, PrintScreen, Insert, Delete, Help, LeftWin, RightWin, Sleep, NumPad0, NumPad1, NumPad2, NumPad3, NumPad4, NumPad5, NumPad6, NumPad7, NumPad8, NumPad9, Multiply, Add, Separator, Subtract, Decimal, Divide, F1, F2, F3, F4, F5, F6, F7, F8, F9, F10, F11, F12, F13, F14, F15, F16, F17, F18, F19, F20, F21, F22, F23, F24, NumLock, Scroll

Supported Pad Buttons:

The following buttons can be referenced in the input config:

Start, Select, Left, Right, Up, Down, A, B, X, Y, L1, R1, L2, R2, L3, R3, Home, Button17, Button18, Button19, Button20, Button21, Button22, Button23, Button24, Button25, Button26, Button27, Button28, Button29, Button30, Button31

It is also possible to bind the analog sticks to events:

LeftStickLeft, LeftStickRight, LeftStickDown, LeftStickUp, RightStickLeft, RightStickRight, RightStickDown, RightStickUp

All key/button names are CASE SENSITIVE!

Multiple Instances

You can load multiple instances of the emulator in a single window, and link them with virtual link cables. The goal of this feature is to offer a streamlined way of working with multiple instances of LSDj. You can create an additional emulator instance using the Project -> Add Instance submenu. Choose one of the following options:

  • Load ROM... - Loads a ROM from disk in to the new instance.
  • Duplicate - Creates an exact copy of the currently active instance by coying its state.

Additional information:

  • You can create up to 4 instances.
  • Instances are linked when the Game Link option is enabled. This has to be done on every instance that is to be linked.
  • Using the default keyboard layout, you can move between instances with the Tab key.

Audio Routing

By default, the output of all instances will be summed together in to a single stereo output. The Project -> Audio Routing menu contains additional options for audio routing:

  • Stereo Mixdown - The default option. Mixes the audio of all instances in to two stereo channels.
  • Two Channels Per Instance - Each instance will output on its own 2 channels. Instance 1 will output on channels 1-2, instance 2 will output on channels 3-4, etc. This may require additional configuration in your DAW. This feature is not available in the standalone version.

MIDI Routing

By default, each instance receives all MIDI messages received on all channels. The Project -> MIDI Routing menu contains additional options for MIDI routing:

  • All Channels to All Instances - The default option. Sends all messages received to all instances.
    • A usage example for this mode could be using LSDj in the Arduinoboy MIDI sync mode, where you want multiple instances to sync to a single C-2 note on.
  • Four Channels Per Instance - Evenly maps MIDI channels across up to four instances.
    • The first instance will receive channels 1-4, the second will receive channels 5-8, etc.
    • This is handy for mGB, since it allows you to evenly split all 16 MIDI channels across 4 mGB instances.
    • Also useful for LSDj in MIDI Map mode, since the mode makes use of 2 channels per instance.
  • One Channel Per Instance - Similar to the mode above but for more simplistic uses.
    • The first instance will receive MIDI from channel 1, the second will receive MIDI from channel 2, etc.
    • A more obvious choice if you want control over individual instances when using the Arduinoboy MIDI sync mode (LSDj).

Multi LSDj Setup

For LSDj versions lower than v6.1.0, one instance of LSDj needs to be set to MASTER and the others need to be set to SLAVE. Versions v6.1.0 and above no longer have these modes, but have a singular LSDJ mode, where the instance that initiates playing automatically becomes the master. It appears there may be additional overhead to this new mode that may make things go slightly out of sync - so it is recommended that if you want perfect sync between more than one instance of LSDj that you use one of the MIDI sync modes. This will sync both instances to your DAW, rather than to each other.

LSDj Integration

When LSDj is detected, additional options are added to the context menus.

Sync Modes

  • Off: No sync with your DAW at all. If you hit play in LSDj it will play regardless of what else is happening.

  • MIDI Sync:

    • Receives MIDI clock from your DAW when the transport is running.
    • If you hit play in LSDj, it will not play until you hit play in your DAW. LSDj should be set to "MIDI" mode on the project page.
    • In this mode LSDj knows nothing about the song position in your DAW, all it knows is that it is receiving a MIDI clock, and that it should play.
  • MIDI Sync (Arduinoboy Variation):

    • Receives MIDI clock from your DAW, but only plays once a C-2 note is received.
    • Additional Arduinoboy options are emulated, full list can be found here.
  • MIDI Map:

    • Receives MIDI clock from your DAW, and plays the row number relative to MIDI notes that you send it. C-0 is row 0, C#-0 is row 1, etc.
    • Notes sent on channel 2 map to rows 128 and above. Other channels are ignored.
    • Rows are stopped when note offs are received, or when you hit stop in your DAW.
    • Requires the Arduinboy build of LSDj.
  • Auto Play:

    • When this option is enabled, RetroPlug will simulate a press of the start button whenever the transport in your DAW is started or stopped.
    • Works in combination with the other sync modes.
    • This option is pretty dumb (it doesnt know if LSDj is playing or not), so it's possible to make it think it is in the wrong state if you manually press Start. If this happens just press Start again.

.sav Manipulation

Thanks to the liblsdj library you are able to list, export, import, load, and delete tracks contained in your LSDj save. The LSDj -> Songs context menu contains these features. Additionally, dragging a .lsdsng file on to the window will add the song to your .sav file and load it immediately (if the .sav has space to contain the song).

Kit Patching

Kits can be patched, deleted, and exported using the LSDj -> Kits menu.

  • Kits can be imported from .kit files, or imported from a previously patched LSDj ROM.
  • To import kits to the next available slot, use the LSDj -> Kits -> Import... menu item. If a kit is already in the ROM it will not be imported. This allows you to import all kits from a ROM that the current ROM does not have without creating duplicates.
  • To patch a specific kit slot, or to replace an existing kit, choose the kit/slot you want to replace in the context menu, and choose Load... or Replace... respectively.
  • Importing kits to a fresh slot requires a reset (this will be done automatically, no song data will be lost). Replacing existing kits does not require a reset, and can be done in realtime while the kit you are patching is currently playing!
  • The patched rom is saved in to your DAWs project file when you hit save, or alternatively in to a .rplg file when you save the project to disk.

The ROM that you loaded from disk isn't actually modified. To save the patched ROM out to disk for use on harware or other emulators, using the LSDj -> Export ROM... menu option.

Updating LSDj

Updating to a new verison of LSDj can be quite cumbersome when your ROM is patched with custom samples, though RetroPlug tries to help make this easy by offering a way of swapping out a ROM and keeping custom samples patched. To do this, use the LSDj -> Upgrade To... menu item and select the new LSDj ROM. Please note that this doesn't upgrade the sav data for your songs, so you will still need to be aware that different LSDj versions may make your songs sound completely different!


  • v1.0.0
    • Mac build
    • 32bit builds
    • Outputs from individual audio channels
    • Move the emulator instance to a different thread (currently runs in the audio thread)
    • Web build
  • v2.0.0
    • Additional emulators. Support for C64, GBA and Megadrive/Genesis is being explored.


  • SameBoy - The emulator itself
  • iPlug2 - Audio plugin framework
  • libsdj - Adds the functionality to manipulate LSDj save files
  • gainput - Gamepad input
  • minizip - Zip compression for project files (containing roms, savs, states, etc)
  • lua 5.3 - Lua scripting language
  • sol - C++ Lua API wrapper
  • spdlog - C++ logging library




  • Visual Studio 2019
  • Clang compiler for Visual Studio (clang-cl). This can be installed with the Visual Studio Installer.
  • Rednex Game Boy Development System. Must be available via your systems PATH variable.
  • Premake 5. Must be available via your systems PATH variable.
  • To build the VST2 target, you need to acquire the VST2 SDK. aeffect.h and affectx.h need to be copied in to thirdparty/iPlug2/Dependencies/IPlug/VST2_SDK/

All other dependencies are included in the repository. Run configure.bat, this will write a project to build/vs2019/RetroPlug.sln. Open and build.


Coming soon!


Please refrain from asking usage questions in GitHub issues, and use them purely for bugs and feature requests. If you need help, the official support chat for this plugin is on the PSG Cabal discord channel:


Q: HALP! The keyboard does not work ;(

A: All hosts are different, and some have restrictions on routing keyboard input in to VST instruments. First, click the center of the window to try and force the host to give focus to the correct control. If that doesn't work, make sure your host is allowing the plugin to receive keyboard input (Renoise has an "Enable keyboard" option, etc). If it still doesn't work, try editing default keyboard mapping in default.lua (written to C:\Users\USERNAME\AppData\Roaming\RetroPlug\input on first run). There are some quirks with certain DAWs...

  • Reaper does not send the ctrl key to VST's, so you'll need to remap that to something different.

If you find you have issues with a particular DAW, please feel free to submit a bug report.

Q: OMG! LSDj does not start when I hit play in my DAW :o

A: Make sure you have the correct sync mode selected in both LSDj, and in the context menu!


If you'd like to support development of RetroPlug, donations of any amount are appreciated! Donate