I use the html viewer app to get .html games to run on my IPhone. I’ve used for this game and a few other similar style IF games and it works well. Sometimes visuals get a bit wonky but text and text formatting usually are fine along with interactive elements within text.
You just download the app and open the .html file and it should load up the same minus some of the visual elements.
I wasn’t able to get the game to launch initially (but also am not the best with iphones!) so that’s kinda what I did to try and work around that. Discord members might have other alternatives or better instructions!
But basically download the game file, save into your phone files folder (or any folder you want on your phone). Once you download the app there’s a button for searching for files on your phone so just navigate to the file and open. Only downside is I haven’t found a way to reliably save progress in the game (but there might be a way within the app - haven’t explored the app to much)