The legality is complex and region-dependent:
Bottom line: You are unlikely to face legal action for downloading an R-User APK for personal, offline use. However, you violate the game’s terms of service, and your account may be banned if you go online with modded features. R-user Games Apk Download
Since you are downloading an APK from outside the Google Play Store, your device will block installation by default. To change this: The legality is complex and region-dependent:
Modifying and distributing copyrighted games without permission is illegal in most countries. As a user, downloading mods exists in a gray area—you’re not cracking the game yourself, but you’re using an unauthorized copy. For free-to-play games, mods violate the Terms of Service. Bottom line: You are unlikely to face legal