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http://mystory.com/story.html?cheatcode=1234
I get the impression that Twine may manipulate the URL and want to be sure that using a url string wouldn't cause problems. I'm using SugarCube (standard history, not hashed), and would read in and process the data from the query string during the StoryInit passage, assigning to variables/option store as appropriate.
Comments
As to SugarCube's hashTag mode. Yes, it's just like the old vanilla headers hash system (no state beyond the path taken). It's still included solely for legacies/compatibilities sake. I strongly recommend against using it.
I've also come up with a way to provide the functionality I was thinking I might need from url hashtags without switching over to that mode (thankfully).