Turning the LEGO Game Boy Into a Cartridge-Playing Handheld is Possible, Just Not Easy

In October 2025, LEGO released its 421-piece Game Boy kit, which is an almost full-size plastic tribute to Nintendo’s 1989 handheld. It’s near enough to the actual thing that the familiar gray shell, pink A and B buttons, cross-shaped control pad, volume wheel, and cartridge slot feel perfect in your hand. Two brick-built carts for Super Mario Land and The Legend of Zelda: Link’s Awakening slide into the back, with lenticular screens displaying the Nintendo logo or brief animated images from both games. Buttons click, but nothing powers on or plays.

Natalie the Nerd, an Australian circuit designer, had already reverse-engineered the original Game Boy PCBs. She shared full scans and schematics on her website and made some translucent boards for other projects. The next natural step was to create a little board that would fit within the LEGO interior. However, space was limited because the original DMG CPU required extra visual memory, which took up a lot of board space. Natalie reasoned that the MGB CPU on the Game Boy Pocket would be much easier to utilize. That chip incorporates video memory, allowing the custom board to be roughly the size of a cartridge. The power source came from one of her current Safer Charger circuits, as it is usually beneficial to reuse existing components whenever possible. Soft latching power controls replaced the prior mechanical switch, and the button matrix and audio pinouts required just little wiring.

The design already had working LEGO buttons and a cartridge slot. The brick controllers were attached to the new board’s inputs using a unique 3D-printed component. The display problem was remedied using a small backlit screen kit, which filled in the display window and replaced the lenticular inserts. A rechargeable battery and USB-C charging complete the power system. The great marvel was that authentic Game Boy cartridges would fit into the rear slot and boot up exactly like they did on the original hardware.

Natalie documented the entire process on her blog, and she is now developing the concept for a kit called Build A Boy. Early versions of this kit will be a drop-in board with minimal soldering required, but later versions will include a 2.7 inch 320×320 display for clean 2x scaling, some nice tactile switches behind the LEGO controls, a speaker, volume control, and an 800mAh battery. For the authentic touch, she located some harvested Pocket CPUs, and all that remains is to get the kits out there, preferably through a Crowd Supply campaign, so that others can try it and turn their own LEGO pieces into fully playable machines.