Transferring an app to new iphone7

[BeefSupreme]

So I've done a little research into this and I think I already know the answer but figured I'd try asking here.

So I have an old free kids game on my 6, not a problem transferring it before with iTunes and 'transfer purchases'

that game is no longer in the App Store. With the way backups are handled now, the actual apps are no longer 'stored' as part of a backup.
Is there any way (iOS 10) to move it from the old phone to the new? There's plenty of software out there to do this with iOS 8 and older, but nothing for 9 and up.

I don't think she'll miss the game, but I'd like to keep it for her since we'd been playing it since she was 18 months old...

 

[jetsam]

You should be able to download any app from the app store that you own, including obsolete ones (but not ones actually banned), if it was originally purchased with an Apple ID you still control.

1. On your new iPhone, open the App store and make sure you're logged in with the Apple ID you used to "purchase" the game
   
2. Select "Updates" from the bottom menu line
3. Touch "Purchased" at the top of the resulting screen.
4. Select "Not on This iPhone" at the top.

The resulting list will give you access to every app you've ever "purchased", even if new users can't download it from the app store anymore.

Following these instructions, I just downloaded an app I had on my iPhone 3G called "Pocket Express", and installed it on my iPhone 7 Plus. The app sort of works, but there's no server support, so it can't actually do anything useful. Nevertheless, Apple still let me download and run it.

Screen shot of newly installed "Pocket Express"

:

 

[BeefSupreme]

You should be able to download any app from the app store that you own, including obsolete ones (but not ones actually banned), if it was originally purchased with an Apple ID you still control.

1. On your new iPhone, open the App store and make sure you're logged in with the Apple ID you used to "purchase" the game
   
2. Select "Updates" from the bottom menu line
3. Touch "Purchased" at the top of the resulting screen.
4. Select "Not on This iPhone" at the top.

The resulting list will give you access to every app you've ever "purchased", even if new users can't download it from the app store anymore.

Following these instructions, I just downloaded an app I had on my iPhone 3G called "Pocket Express", and installed it on my iPhone 7 Plus. The app sort of works, but there's no server support, so it can't actually do anything useful. Nevertheless, Apple still let me download and run it.

Screen shot of newly installed "Pocket Express"View attachment 657865 :

I didn't know this existed! Huge list and while I found some old stuff I wanted back, the one game I was looking for is not there. It's definitely on this Apple ID, as I've only had this one since the first iPhone. I don't get it. Even the old apple app that I used to get my free case for my iPhone 4 antennae gate, was there available for download.
Thank you for the suggestion though! It'll come handy in the future for sure.

Any other ideas out there?