This extension will work with any CoreRPG based ruleset. To use this you'll need to be using a CoreRPG based ruleset using the current CoreRPG version. The Savage Worlds ruleset is not compatible as it's not a standard CoreRPG ruleset. The AD&D 2E ruleset includes this feature so is unnecessary.

What does it do? This extension, when enabled, will show a Crown above whatever token currently has initiative.

Why? Well, the tiny white ring is way to subtle for me to notice at times and right now there is no way in the API to tweak that (make it bigger or a different color) as far as I know. This has something to do with scaling and token/image sizes but... either way, this was my way to resolve it for my own use.

Enable the extension, Cycle through initiative in the CT and you'll see the new icon on the token with initiative. 

You can read more about the extension on the forum thread for the extension here.