Zero-K would be my RTS recommendation (it's open source!): https://zero-k.info/ https://zero-k.info/ For ARPGs, the elephant in the room is Path of Exile: http

Zero-K would be my RTS recommendation (it's open source!): https://zero-k.info/ https://zero-k.info/ For ARPGs, the elephant in the room is Path of Exile: https://www.pathofexile.com/ https://www.pathofexile.com/ Neither is really viable for mobile, but I didn't quite catch whether that was a major criterion for you.