Getting really excited for the release....
Btw are you running a sale on the basegame? It could draw in loads of new players. (who then buy the expantion, because thats a nobrainer).

Imo the button on the confirmation tab of the undo action that is now called " back " should be called " Cancel ".
The undo action itself is some sort of "back" feature that could confuse people. Really you try to cancel the undo action, not going back to anything.

Aside from that, great stuff and ...