12 data formats

12 — Data Formats

Every persistence format used by Simple Launcher and where it lives. Related: 05 — Configuration · 07 — Core Services

Format map

Format	Files	Written/read by
XML (LINQ-to-XML)	settings.xml, system.xml, emulator *.ini-adjacent XML (Ares settings.bml, Cemu settings.xml)	SettingsManagerService, SystemConfigurationWriterService, EmulatorXmlHelpers, inject services
MessagePack	favorites.dat, playhistory.dat, history.dat, mame.dat, RetroAchievements.dat, all_ra_games.dat	FavoritesManager, PlayHistoryManager, RomHistoryLoader, MameManagerService, RetroAchievementsManager
SQLite	Amazon Games DB (read-only), Stella stella.sqlite3 (settings upserts)	ScanAmazonGames (Microsoft.Data.Sqlite), StellaConfigurationService (SourceGear.sqlite3)
JSON	appsettings.json (config), LauncherInstalled.dat/manifests (Epic), GOG .info, Humble config.json, itch .itch.toml-adjacent, Mesen settings.json, BizHawk config.ini (JSON), API payloads	app config, scanners, MesenConfigurationService, RetroAchievementsEmulatorConfiguratorService, JsonSerializer
YAML	RPCS3 config.yml	RPCS3ConfigurationService (YamlDotNet round-trip)
TOML	Xenia xenia[-canary].config.toml, Yumir Ymir.toml	XeniaConfigurationService, YumirConfigurationService (Tomlyn)
Plain text	parameters.md, WhatsNew.md, .extraction_in_progress marker, version.txt, batch files	help/update/extraction/updater
INI	most emulator configs (retroarch.cfg, PCSX2.ini, Dolphin.ini, settings.ini…)	InjectEmulatorConfig\* + RA configurator INI helpers

MessagePack data files

File	Content	Class
favorites.dat	favorite games (system + filename)	FavoritesManager (Services\Favorites\, app)
playhistory.dat	play sessions: date, play count, total seconds	PlayHistoryManager (Services\PlayHistory\, app)
history.dat	ROM history database (HistoryData/EntryData/ItemData/SoftwareData)	RomHistoryLoader (Core)
mame.dat	MAME machines + software-list descriptions	MameManagerService (Core)
RetroAchievements.dat	RA game info, achievements, progress	RetroAchievementsManager (Core)
all_ra_games.dat	full RA game database (built by Tools\RetroAchievements.DataFetcher)	RA fetcher tool

history.xml → history.dat migration (RomHistoryLoader): the loader prefers history.dat (faster, smaller); if absent it falls back to history.xml (legacy). Tools\XmlToBinaryConverter performs the conversion.

BoolConverter (Core Models\BoolConverter.cs) handles APIs that return booleans as numbers (0/1).

settings.xml details

• LINQ-to-XML, root <Application>; atomic save via temp file + File.Move with 3 retries + exponential backoff; portable → LocalAppData fallback (SettingsManagerService.SaveAsync, :565-685).
• Emulator settings blocks (EmulatorSettings\ ×21) are serialized as child elements; RA credentials are DPAPI-encrypted (Base64) before writing (:717-719).

system.xml details

• SystemConfigs root; entries alphabetically sorted (ordinal-ignore-case); UTF-8, 2-space indent; XDeclaration ensured; retry ×3 with 500 ms backoff; temp file + File.Move; empty or corrupt root replaced with a fresh <SystemConfigs/>. See 05 — Configuration.

Emulator config files (injected)

Emulator	File	Parser
Ares	settings.bml	XML
Azahar / DuckStation / Flycast / RetroArch / Redream / Dolphin / Blastem / Supermodel / Sega Model 2 / Raine / Mednafen / Daphne	*.ini/*.cfg	custom INI readers/writers (sections, insert/append)
PCSX2	PCSX2.ini	INI with [Achievements] etc.
RPCS3	config.yml	YamlDotNet (round-trip preserves structure)
Xenia / Yumir	*.toml	Tomlyn
Mesen	settings.json	System.Text.Json.Nodes
Stella	stella.sqlite3	SQLite upserts (sample DB copied when missing)
BizHawk (RA)	config.ini (JSON)	JsonNode

Missing files are restored from samples\{Emulator}\{file} (copied from the app's samples\ folder).

Related docs

• 05 — Configuration
• 09 — RetroAchievements
• 11 — Bundled Tools