As far as I know, Microsoft recently stopped supporting that platform, and Unity itself does, but the thing is that I have the requeriment from my client to also support windows phone 8.1 devices (along Android, iOS and WP10). Can I still make a build for WP8 using old Unity versions? And furthermore, can I still uploading contents to the WP 8.1 store, or is it already impossible to do?
In short, should I tell my client to forget about it?