Where apps hide your files
OpenEmu keeps nearly everything in one folder in your user Library, so a backup or a move to a new Mac is mostly one copy. The catch is that games, save states and screenshots sit in different subfolders.
~/Library/Application Support/OpenEmuThe ~/Library folder is hidden by default. In Finder choose Go > Go to Folder (⇧⌘G), paste the path and press Return, or in Terminal run:
open ~/Library/Application\ Support/OpenEmuThese locations come from OpenEmu's open-source code on GitHub, which defines the folder names the app uses. OpenEmu was not installed on the Mac used for this guide, so nothing here is a local check.
| Folder or file | What it holds |
|---|---|
Game Library/ | The library database (Library.storedata) and, by default, your imported games |
Game Library/roms/ | The game files, in subfolders by system, plus unsorted |
Game Library/Artwork/ | Cover art |
Save States/ | Save states, in a folder per system, then per game |
Screenshots/ | Screenshots, saved as PNG files |
BIOS/ | BIOS files the emulator cores need |
Cores/ | The emulator cores OpenEmu downloaded |
<core name>/Battery Saves/ | In-game saves, one folder per emulator core |
The roms folder is only filled when OpenEmu copies games into its library, which it does by default (the Copy files to Game Library folder when adding to library checkbox in the Library preferences). If you turned that off, the library points at games where they already were on disk. In that case a game's real location is shown by choosing Show in Finder from the game's right-click menu.
States are stored as Save States/<system name>/<game name>/, and each state is a package with the extension .oesavestate holding the state data (State), a ScreenShot and an Info.plist. The system folder uses the display name of the core's system, and the game folder uses the game's file name without its extension. A package is a folder that Finder shows as one file, so use Show Package Contents if you want to see inside. Do not edit it.
OpenEmu also treats the Auto Save State and Quick Save State specially: they are not listed under Play Save Games, and the Quick Save State is reached from the disk menu in the game's HUD. In the library window, the Save States view lists every state, and right-clicking one offers Show in Finder. The OpenEmu wiki says a manual state is named by you, or by date and time if you leave the name blank.
These are OpenEmu's own save states. In-game battery saves, the kind a cartridge writes when you save inside the game, are separate. Each core keeps them in its own folder:
~/Library/Application Support/OpenEmu/<core name>/Battery Saves/Back those up too, or you lose in-game progress that was never made into a save state.
Screenshots go to ~/Library/Application Support/OpenEmu/Screenshots as PNG files. The Screenshots view in the library window lists them, and Show in Finder on one reveals the file. You can drag them from the folder like any other image.
Some systems need a BIOS file, and OpenEmu's wiki is firm about how to add one: do not copy it into the BIOS folder yourself. Install the core for that system first, then drag the BIOS file onto the OpenEmu library window the way you add a game. OpenEmu checks the file's MD5 hash and the accepted file name, then places it in BIOS/ for you. To check a hash before trying, run:
md5 /path/to/fileOpen OpenEmu's preferences (OpenEmu > Preferences, which newer macOS versions may show as Settings) and choose the Library tab. Game Library Folder Location shows where the library is, with Move... and Move to Default Location buttons. OpenEmu warns that moving the library is not recommended, because the database file can be corrupted in folders managed by cloud sync software such as iCloud Drive, on network drives, and (the warning adds) on external USB drives. It also warns against sharing one library between computers or users.
Note what this setting moves. In the source code, only the library folder (Game Library, with the games and artwork) follows it. Save states and screenshots use their own default folders in OpenEmu, so moving the library does not take them along.
~/Library/Application Support/OpenEmu folder to the new Mac, into the same place.Copy the entire folder rather than pieces, so the database, games, states and battery saves stay in step. Time Machine includes this folder by default.
The games are usually the largest part, then save states, since every state package carries its own screenshot. Measure with:
du -sh ~/Library/Application\ Support/OpenEmu/*Remove games inside OpenEmu (right-click a game and choose Delete Game), so the database stays consistent. OpenEmu only moves files that are inside its library folder to the Trash. Deleting files from roms in Finder leaves the library listing games that no longer exist.
Spotlight and Finder searches leave out results inside ~/Library, and game files are often named by the dump, not the title. A save state is a package folder, so it appears as one item with a name you did not choose.
Typing oesavestate into Everywhere lists every save state package by name, and typing a game's file name finds both the game and its state folder, even inside ~/Library/Application Support. Press ⌘↵ to reveal one in Finder. It matches file names only, so it will not find a game by what is inside it.
By default in ~/Library/Application Support/OpenEmu/Game Library, with the game files in a roms subfolder by system. If you turned off copying to the library, games stay where they were.
In ~/Library/Application Support/OpenEmu/Save States, in a folder per system and then per game. Each state is an .oesavestate package.
Each emulator core keeps them in ~/Library/Application Support/OpenEmu/<core name>/Battery Saves/, separate from save states. Copy those folders too when you back up.
The Library tab in OpenEmu's preferences has a Move button, but OpenEmu warns against cloud-synced folders such as iCloud Drive, network drives and external USB drives because the database can be corrupted. Save states and screenshots do not move with it.
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