There are other flash "replacements", the one I like the most being Haxe [0] (transpiler to flash bytecode, javascript, and more) + OpenFL [1].

OpenFL replicates flash API [2], can work with Adobe Animate (formerly flash), and can use swf assets [3]. There are also converters from AS3 to Haxe, both available and not yet released (like the one used to migrate Forge of Empires [4]).

Haxe + OpenFL can export to flash player, HTML5 but also to native (desktop, mobile, consoles).

[0]: https://haxe.org [1]: https://openfl.org [2]: https://api.openfl.org/ [3]: https://www.openfl.org/learn/haxelib/tutorials/using-swf-ass... [4]: https://haxe.org/videos/conferences/haxeup-sessions-2019/dan...