thank you very much for notifying the malfunction with Firefox. It seems that Firefox has been updated in a way that broke the QR Scanner.
Before today, we were using https://webqr.com/ project but now it doesn't work with Safari (IOS) nor Firefox. Now we have reimplemented the QR support using the library at https://schmich.github.io/instascan/ that aparently works with Chrome and Firefox. Unfortunately, according to Instascan documentation:
"Instascan works on non-iOS platforms in any browser that supports the WebRTC/getUserMedia API, which currently includes Chome, Firefox, Opera, and Edge. IE and Safari are not supported.
Instascan does not work on iOS since Apple does not yet support WebRTC in WebKit and forces other browser vendors (Chrome, Firefox, Opera) to use their implementation of WebKit. Apple is actively working on WebRTC support in WebKit."
Actually, Edge doesn't support WebRTC.
We have just released the version 1.2.13 that works with Chrome and Firefox in PCs and Android phones (please report your experience here https://github.com/juacas/moodle-mod_treasurehunt/issues/14).
About the Mobile App: We worked hard to provide a seamless experience using only a browser for playing the treasurehunt. We believe that students and teachers should be able to use the activity without installing native apps.
Moreover, we have no resources to work on porting to an application framework. Maybe someone in the community would collaborate on that.
PD: Don't forget to use a server with https enabled.