A new version of ATBTT has been sent to Epic and should hopefully be live sometime this week! This is a new feature update, though most of the features are changes to the structure of the toolkit to allow various game specific features to more easily be added rather than ready-to-use additions, though there are a few such features additions as well.
This version is built with UE4.21 and will be the version you download if you select 4.21 when creating a project with the toolkit. If you prefer to keep using the previous version of the toolkit in UE4.21, simply create a ATBTT project in 4.20 and convert it to 4.21, which does not seem to cause any issues.
I am choosing to call this version of the toolkit 2.0. And yes, I know that it is fine to make version 1.10 after version 1.9 (the last version), but I feel the toolkit has gone through so many changes that it is about time to slap a big 2.0 on it; not to mention it will add another T to the name of the toolkit, making it even more difficult to pronounce 
Even though this is a fairly substantial update, it is certainly not the biggest update I’ve made, with 1.8 certainly taking that prize, so don’t let the name fool you. Nevertheless I hope people will appreciate all the new changes and additions and realize the new possibilities that open up thanks to some of these changes.
Since I have altered some core aspects of the toolkit, this will unfortunately be a fairly difficult version to update an old project to if you’ve made a lot of modifications. My recommendation for that is as always to port over your own additions manually and integrate them into the new toolkit rather than going the other way around, as you presumably know your own additions better than you know mine. Still, I’ve tried to be as transparent as I can with what has changed, by adding boolean version markers and commenting. Below is a list with the highlights of what has been changed in this update, though you can see a more complete list at my Trello.
v2.0 (files pending - sent to Epic 13.11.18)
- Refactored how tiles are indexed to allow for adding tiles beyond the edge of the grid manager at runtime.
- Refactored multi-level heightmaps so that they are predictably indexed based on their relative height.
- Added subgrids, which are blueprints that can be placed outside the grid and treated as being part of the grid.
- Moved hexagonal grid math to separate child blueprint.
- Hex grid math now uses a cube coordinate system, simplifying math and making it more efficient. Thanks to Amit Patel for his useful guides on hex math.
- Switched the skeletal mesh of BP_Unit_Anim and its children to the default UE4 mannequin instead of the mobile mannequin.
- Experimental: Added outline post processing material for displaying move range as an outline. Thanks to Tom Looman for his tutorial.
- Experimental: Added new blueprints (ladders and teleforters) for automatically adding custom tile edges.
- Experimental: Added new experimental unit, which has movement animations that change based on the underlying array (utilizing a new SpecialEdges TMap in BP_GridManager)