No dice :( I get a getlengthfailed error when I open through njws, and when I open the game file itself I get an error reading "The application “Game” can’t be opened."
I got it running by moving the "Game" executable file somewhere outside the game's folder (and outside the Downloads folder). Don't ask me how it works, but almost every game using this engine seems to have this problem on Mac.
Unfortunately all I get now is an empty window saying "Your file was not found" with a path ending with "www/index.html" as window title.
Edit: the 3/4 spell swap demo runs perfectly fine though