Install Realmgate
Three ways to get it on a phone. All the same app — the difference is only how it is installed.
iPhone
Open this site in Safari, then Share → Add to Home Screen.
It has to be Safari; Chrome on iOS cannot install web apps.
Apple only allows real .ipa apps to be built on a Mac and
distributed through the App Store or a developer account, so this is the
iPhone route — you still get the icon, full screen and offline sheets.
Android — the easy way
Open this site in Chrome and take the Install app prompt, or ⋮ → Add to Home Screen.
Nothing to sideload, and it updates itself whenever the site does.
Android — the real APK
Download realmgate-1.0.0.apk 1.5 MB
Android will warn you about installing from an unknown source, because this is not from the Play Store. You will need to allow your browser to install apps once, in the prompt it shows you.
The Chrome install and the APK behave almost identically. The APK is worth it if you want a genuine entry in the app drawer and app switcher, or want to pass it to someone directly. Otherwise Add to Home Screen is less fuss.
Either way, open Spearhead once while you have signal and tap Save all sheets, so they work at a club with no connection.