To get around the persistent connection problem @Tinuviel mentioned, you really need a dedicated mobile app. (Not just a web app.)
This is a huge, possibly-insurmountable, challenge for several reasons:
- Most MU servers don't support that kind of interaction; they're designed around telnet connections. The back-end would have to be changed. Unless someone came up with a centralized API, it would lead to different mobile apps for Ares, Evennia, Rhost, etc.
- Even if someone came up with a centralized API for the main game functions, MUSHes are heavily customized. Your mobile app would have to account for that somehow.
If we handwave those challenges away, an ideal mobile MU app would look to apps like Discord and Slack. MUs are, after all, little more than glorified chat engines.
This would lead you to things like clickable menus that hide away when you're not using them; persistent background connections with intelligent notifications; a streamlined chat interface; etc.
Unfortunately, all of that is unlikely to happen. I think MUSHing, like many other kinds of video games and apps, is going to stay in the realm of things best done on non-mobile devices for the forseeable future.