Current:
https://www.hiveworkshop.com/attachments/ggggggg-png.403597/
Proposed:
https://www.hiveworkshop.com/attachments/zoom-feature-redesign2-png.403598/
For Mapmakers:
You are looking to create two fields in the world editor > Advanced > Gameplay Constants.
Since it’s a balance setting you can set it enabled in maps using melee balance, but disabled in customs by default.
That’s the correct way to implement this. You don’t break old maps, but still let new ones enable it if they want to support it. This is basically how it has been done with all changes in the past that would affect custom games.
It is critically important that this ideology be maintained if custom games are to continue functioning.
Showcase:
https://www.hiveworkshop.com/attachments/world-editor3-png.403599/