Quick update:
I finished phase 1 of development, which is to create a working app without any of the paid features.
I've signed up to the Apple Developer program and I'm in the process of getting a build of the app uploaded for testing. Once that is done I'll be clearer about how to get people to sign up for a bit of testing. I'll make a new post about that when I'm ready.
In the meantime I'm working on phase 2, which is the remaining locked paid content (custom stuff, pets etc). I've got another couple of weeks before Guns and Gears Remastered so hopefully will get the bulk of it done before then.
As ever, thanks for your continued support.