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gacubeboy emulator with IOSU hack
Downloadable via the Homebrew App Store

The gacubeboy emulator with IOSU hack was made by brienj, who also designed the GX2 interface for CHIP-8_Emulator. He quickly developed this emulator using the framework used in CHIP-8 to demonstrate how pluggable the emulator frame was. The core of the emulator was ported by brienj himself after looking at various Z80 emulation docs.


This emulator was created in less than 8 hours of actual programming. The Gameboy ROM compatibility isn't the best and it has no sound, but was made to prove that even if you half-heartedly attempt homebrew, you CAN make something. A main point with the emulator's release+title was to demonstrate that a Security OS (aka IOSU) exploit is not required to make homebrew/emulators.

Put the gacubeboy.elf file in the sd:/wiiu/apps/gacubeboy/ folder of your SD card. Put all of your Gameboy roms in the sd:/roms/gb/ folder of the SD card with the .gb extension. Sub-folders are acceptable, but not needed. Keep the number of ROM files less than 200 for best results.




Load a ROM and press the Play button. If you select the play button with a WiiMote, that WiiMote will be used as the controller, with sideways orientation. The A and B buttons will be swapped with the 1 and 2 buttons if you play with a WiiMote. Once a game is started the Play button becomes a Pause button. If the game stops playing, that means it crashed, and either the ROM isn't supported or something crazy just happened. Just load a different ROM and try again. Not every game is supported. Plus button is the Start button and Minus button is the Select button.

New in Version 9000, press L on the Gamepad, or A on the WiiMote, to toggle Full Screen.


When the emulator is launched, you will be asked to select a ROM image. Use the +Control Pad to select a ROM and press A to launch it.

The gameboy buttons are mapped to their Wii U counterparts. An onscreen button can be used to enter/exit full screen mode.

At any time during a program, you can simply press the HOME button to quit the program and return to the Homebrew Launcher.

Wii U GamePad Action
Wii U GamePad HOME Button Exit the emulator and return to the Homebrew Launcher

Naming controversy

When the emulator was posted to GBATemp, the thread gained controversy due to its name. More specifically, the emulator was not "an iosu hack" as some users were led to believe. When brienj met criticism for the name of the emulator and title of the thread, this was his response:

I don't care if the thread title is changed, I can't change it myself, but the actual name of this emulator isn't changing, it's the name I want it to be called, but the next one is not going to be named over a meme.

Implying that the jokey nature of the emulator's title/art is effective and intentionally the desired reaction when coupled with the limited functionality that was being offered.


Nothing, the engine is going to be a port next time. I don't have time to build a Gameboy engine from scratch and want to get a better version out soon with better ROM support and sound.


-dimok for all of his HBL code which makes it simple to build homebrew



  • Added Full Screen key press


  • Initial release
  • Basic ROM support, no sound