Where a Game Boy ROM actually runs

A finished Retroable game is one .gb file. The browser player on the game page loads that file into an emulator. The emulator pretends to be the original chip, a Sharp LR35902 running at about 4.19 MHz. You are not playing a remake. You are playing the ROM.

The same file opens in a desktop emulator. SameBoy and mGBA are two that people use. Sound can differ, because each player buffers audio in its own way. If the desktop version is clean and the website crackles, the ROM is not the broken part. The player is.

On hardware, you copy the .gb onto a flash cartridge and put that cartridge in a Game Boy. A flash cartridge is a blank you can rewrite. It is not the cartridge Retroable manufactures. The one we ship is made for a single game, with its label, and you do not wipe it for the next ROM.

Saves do not live inside the .gb file. A game that remembers progress keeps it in cartridge RAM. Emulators store that RAM in a sidecar, often a .sav file next to the ROM. Download the .gb alone and you take the game, not the high score.

The keyboard on the website is only a front for the Game Boy's switches. WASD and the arrow keys are the D-pad. Space is A, Ctrl is B, C is Select, and V or Enter is Start. The ROM sees the switches, not the key names.