How to open an unsupported filetype in an app.

[Bubbleawsome]

I'm trying to open a .nds file in an app that doesn't think it supports it. I know for a fact it does, and now I'm trying to get it to open. iOS 9 doesn't put the app in the "Open In" menu though. Any way to force it?

 

[Rakehellion]

Change the file type extension? Can you add the file to the app via iTunes?