You can run VCMI on iOS 12.0 and later, all devices are supported. If you wish to run on iOS 10 or 11, you should build from source, see How to build VCMI (iOS).
The latest release (recommended): https://github.com/vcmi/vcmi/releases/latest
Daily builds: https://builds.vcmi.download/branch/develop/iOS/
To run on a non-jailbroken device you need to sign the IPA file, you have the following options:
your.bundle.id with something like
com.MY-NAME.vcmi. After that use the above signer tool.Note: if you don't need in-game videos, you can omit downloading/copying file VIDEO.VID from data folder - it will save your time and space. The same applies to the Mp3 directory.
To play the game, you need to upload HoMM3 data files - Data, Maps and Mp3 directories - to the device. Use Finder (or iTunes, if you're on Windows or your macOS is 10.14 or earlier) for that. You can also add various mods by uploading Mods directory. Follow official Apple guide and place files into VCMI app. Unfortunately, Finder doesn't display copy progress, give it about 10 minutes to finish.
If you have data somewhere on device or in shared folder or you have downloaded it, you can copy it directly on your iPhone/iPad using Files application.
Just move/copy Data, Maps and Mp3 folders into vcmi application - it will be visible in Files along with other applications' folders.
You can also upload files with Xcode. You need to prepare "container" for that.
You can start game directly (avoiding the launcher) by changing setting in iOS Settings app - VCMI.