Amazing! Now you need to find a device that can still run it :-)

Probably safest to run it in an emulator with no internet access, given where it was found.

APKs are signed so assuming OP can verify his own certificate he might be lucky enough to not have to dig that deep.

If it's being distributed by a piracy site, and the game had any sort of protection to make sure people actually bought it, then probably they're storing/offering a pre-cracked version, which certainly shouldn't (or wouldn't) be signed by anyone.

This sort of protection is rather rare for android apps.

Emulator with gen ai tool! That's it! Sanitize it then fix.

jadx can probably disassemble it pretty thoroughly. I think you can give it the APK directly, or just unzip it and give it the classes.dex.

Assuming everything goes smoothly, you could potentially resurrect a compilable project in about a man-week, or two, or three...

The Internet Archive already has some emulation support, perhaps Android support is needed? If OP is willing to transfer the copyright to the Archive for $1, I'm happy to facilitate so it has a permanent home.

https://archive.org/details/howtodoupload

(i have archived the APK in Wayback just in case the source in this thread disappears)

That would be great. Is there a way I can reach out to you by email for more info? (my email is my hn username at gmail)