Six months of running a GBA emulator

I shipped GoGBA (Android + iOS) to both stores in late December 2025. Six months in: MAU peaked at 8.3k, currently steady around 7.4k. No paid advertising, ever. This is a write-up of what the six months actually involved. I'll be specific about the technical work, and equally specific about the mistake that cost me RetroAchievements hardcore certification — because that part is the most useful thing here for anyone building in this space. Why GBA only I grew up on a GBA — Super Robot Wars, Fire Emblem, Pokémon, Castlevania, Zelda. Later NDS/3DS/PSP/Vita/Switch arrived and the GBA did its job and retired. On PC the emulator I remember is VisualBoyAdvance. I've used GBA, NDS and PSP emulators on phones. I kept coming back to GBA, for four reasons that are all practical rather than nostalgic: Pixel art holds up. Personal taste, no defense offered. Battery. A GBA game survives a long-haul flight. Single screen. The remaining screen space is exactly where virtual buttons want to go. NDS dual-screen on a phone is always a compromise. ROM hacks. The GBA hack scene is the richest of any handheld. Point 3 is the one that made me build something: GBA is the only handheld whose form factor natively fits a phone. That's a product observation, not sentiment. What existing emulators get wrong (for me) I used the main ones on both platforms: Delta and Linkboy on iOS; Pizzaboy, Linkboy and Lemuroid on Android. Lemuroid is open source and a lot of shipped emulators are built on it. They're all good. Every one of them had small things that annoyed me. The only genuinely cross-platform one is Linkboy (formerly MyBoy), but its configuration surface is extremely deep — second only to RetroArch in complexity. That's the gap. Everyone was solving "can it run" and "can it be tuned perfectly." Nobody was solving "pick it up and play." The methodology was just dogfooding I'm a Flutter GDE and tech lead for a 40-person cross-platform team; GoGBA was a solo test of that experience. The only r