You can click on a menu at the top right to bring up a list of stacks. It simulates HyperCard directly rather than simulating an entire Macintosh, so it’s a lot faster and more convenient to work with. Not all stacks are compatible, but there’s a wide selection.
HyperCard On The Archive - https://news.ycombinator.com/item?id=14985604 - Aug 2017 (115 comments)
They no longer have a free version, but to me it is well worth the approx $100/year.
and an active fork https://github.com/OpenXTalk-org/OpenXtalk-IDE-DontPanicEdit...
They didn't make their own engine until the sequel, Riven, and the "Myst Masterpiece" remake.
Ok... weird GUI behavior, thanks for the help. I had no expectation that the above menus had anything to do with the open window. Especially when if you click on them, they don't open.
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Steps to reproduce:
Open HyperCard 2.0
[1] https://archive.org/details/hypercard_hypercard-20-macintalk
Boots into Macintosh, awesome!
Open "Hypercard Sys 7" diskette from upper right corner
Open up Hypercard 2.4 folder
Open "About HyperCard"
Shows About Hypercard screen, no way to close it. The Close box in the upper right does nothing. Escape does nothing, clicking incessantly does nothing.