~/.local/share/perfectdark on Linux
AppData/Roaming/perfectdark on Windows
on Windows if the game has write access to the working directory it will save there by default, otherwise it will save to AppData
on Linux the game will save to the working directory if there is already a config there, otherwise it will save to ~
additionally the ROM/data files will be loaded from wherever they're found, working directory taking priority
--log: logs messages to pd.log
--boot-stage N: sets initial stage number to N (MP stages will crash or hang if booted like this)
--no-sound: disable sound
--rom-file S: set ROM filename
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