Conclusion: Follow The Official No-Intro Convention.
There’s a project called No-Intro that catalogs digital games and provides databases, and the document linked above comes from them.
It’s the standard naming convention across various emulator-related communities, starting with RetroArch. Following it makes it easier for programs that automatically assign things like box art to identify your games, so sticking to it is probably the safe choice.
Here’s a rough summary of what it says.
ROM File Naming Convention
- Only 7-bit ASCII characters are allowed.
- a–z
- A–Z
- 0–9
- space
$ ! # % ' ( ) + , - . ; = @ [ ] ^ _ { } ~
- The following ASCII characters cannot be used:
\ / : * ? " < > |+ “`”
- Filenames cannot begin with a space or
. - Generally, proper nouns, adjectives, and verbs are all capitalized.
- Articles and conjunctions are lowercased, except at the start of the title.
- Examples:
- Adventure of the Hero
- Riding in a Car
- Travel from Earth to the Moon
- From Earth…
- Into the Darkness…
- Examples:
- Writing the entire title in uppercase should be avoided as much as possible, unless it’s an acronym.
- If the first word is a common article, it is moved to the end of the main title and separated by a comma. (Retronian’s note: “Seriously?”)
- Example 1: The Legend of Zelda → Legend of Zelda, The
- Example 2: A Man Born in Hell → Man Born in Hell, A
- Subtitles and pre-titles are always separated from the main title by a hyphen “ - “. Titles that use other separators (for example colons or “~ subtitle ~” style) are converted to the hyphen style.
- Example 1: Castlevania II - Belmont’s Revenge
- Example 2: Double Dragon - The Ultimate Team
- Example 3: Legend of Zelda, The - A Link to the Past
- Japanese characters should be romanized using the Hepburn system.
Things That Caught My Eye
The Legend of Zelda → Legend of Zelda, The — seriously, for real?
And, obviously, you can’t use Japanese characters in filenames. The hyphen style for subtitles is a good thing to keep in mind.