Fors FMS Turns the Game Boy Advance into an FM Groovebox for Just $10
nanoloop Gets Some Competition: Lo-Bit Club Releases a 2-Op FM Synth for the GBA
3,0 / 5,0 | 
If you like making music on old gaming hardware and have a soft spot for lo-fi sounds, today is a good day. Ess Mattisson, known from Fors and previously involved in the original Elektron Digitone, has released FMS through Lo-Bit Club: a piece of software that turns the Game Boy Advance into a compact FM groovebox. It runs on original GBA hardware, compatible devices like the Analogue Pocket, and GBA emulators. 10$ on itch.io.
Fors FMS: Everything You Need to Know About the FM Groovebox for Game Boy Advance
FMS: 2-Op FM Synthesis on the Game Boy Advance
Ess Mattisson is a developer who moves between different worlds comfortably. He worked on the original Elektron Digitone, and through Fors he releases plugins and Max for Live devices. He’s also a longstanding fan of the chiptune scene, so a GBA release through Lo-Bit Club makes a lot of sense once you know the backstory.
FMS is distributed via itch.io and turns the Game Boy Advance into a groovebox built around 2-operator FM synthesis, which according to the developer is a first for the GBA hardware. The software isn’t available as a cartridge and needs to be loaded via a flash cart (such as those from Krikzz) onto original hardware. Beyond that, it’s also compatible with the Analogue Pocket and with GBA emulators like mGBA, which are available on pretty much every platform at this point, including smartphones. So technically you can run this groovebox in your pocket on a device you already own.
The whole focus is on fast, intuitive music-making with an eye toward live performance. There’s a real scene of people who play with vintage gaming hardware in front of audiences, and FMS fits right into that context.
A Sequencer With Clear Elektron DNA
FMS offers four FM tracks alongside one noise channel. The sequencer is where the Elektron influence shows up clearly: each step can trigger its own sound, each track can have its own independent length, and there’s support for rate, shuffle, and probability-style functions. Notes can be quantized to scales, chords are possible, and the note echo effect generates arpeggios as well as delay and echo-style textures.
Patterns can be combined and played back either randomly or in sequence. Snapshots are also supported and can be switched on the fly, which is exactly the kind of feature that makes the difference in a live set.
The sync options are a genuine highlight. You can sync to another GBA over the Link port, use a clock signal via custom-built connectors, or receive MIDI clock via Arduinoboy cables or the Analogue Pocket’s MIDI support. That’s a lot of flexibility for a $10 piece of software running on a 2001 handheld console.
Verdict
FMS is a clever, well-thought-out release that slots into a niche that was clearly waiting to be filled. The combination of proper FM synthesis, Elektron-influenced sequencing, and flexible sync options on GBA hardware is genuinely impressive, especially at this price. Whether you’re an Analogue Pocket owner, an emulator enthusiast, or someone who still has a flash cart sitting in a drawer, this is worth ten dollars without much hesitation.
Price and Availability
FMS is available now on itch.io for $10, with an optional pay-what-you-want model above that. It requires a flash cart for use on original GBA hardware or compatible devices. The full online manual is available at lo-bit.club/fms/guide.
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