The final release date for the map editor is June 23rd. It was previously announced for late May / early June, but the editor requires some additional work to be ready for public release.
Upcoming Update
The June 23rd update will include:
- Ability to create skirmish maps, multi-player maps, as well as custom games, and missions;
- Ability to use your own custom units within the maps and games;
- Scripting support for custom games, and missions;
- Workshop support for custom map sharing.
Later
Support for custom campaigns requires additional work, and will be coming in a later update, which is currently planned for late July. As always, a precise release date announcement will follow!