There is one more requirement for the games I could use, I guess: I do need to access the data rather quickly, meaning I need to be able to download the HTML (+ javascript etc.) game files locally and make the game data (HTML + js + … source) a part of an open-source repository (currently under MIT license). I don’t really know how the customs in the world of IF licenses. If there is no mention of licensing, can I use the game source code?
I would obviously try to contact the author, but they might not always reply. Thank you!
The most common case is that authors release the compiled game file without source code.
If the game source code is available, there’s usually a license attached. (Zork and Colossal Cave are exceptions, as they predate the codification of “open source” as a legal device.) (Although gitlab.com/esr/open-adventure popped up recently, as it happens.)