I disagree. If you follow the game engine analogy/thought experiment, I think there's much more that could be done. There's a language, yes. There's also a run

I disagree. If you follow the game engine analogy/thought experiment, I think there's much more that could be done. There's a language, yes. There's also a runtime. There may be an interpreter depending on the language. There's probably also a defined way of getting UI on to the screen in a platform independent way. There's probably also higher level concepts, maybe something that works a bit like a service worker, to use web terminology. There's likely to be a database of some sort, an app deployment system, software updates. I'm not proposing a specific technology, but rather pointing out that there are a lot of parallels, and by realising that we're now using web technologies for shipping apps that aren't otherwise websites, maybe we could open up a lot of new potential solutions that might be even better.