Just had a couple of thoughts I'd find quite cool;
At the end of a game, it would be brilliant if the game showed the amount of overkill achieved. So in a destruction win, the amount by which your attack exceeded their tower; in construction wins the amount by which you went over 100; and in resource victories the amount of resources (or stock?) by which you went over 400.
We could even make it so these give you bonus exp. either just a fixed amount (10 overkill gives 10exp), or as achievements (exp. x1.2 if overkill > N). Anyone else like this?
Secondly, if it were possible to finish your turn after the game is over, for example killing an opponent with Swift card. This doesn't really make too much sense without the overkill being implemented.
My only concern is that it might encourage people to try too hard for overkill and play in a very un-fun manner (desolator deck, keeping the enemy pinned down until you have 7swifts and a Dragon Squadron sort of thing). But hopefully that won't happen and the function could always be removed if it proves to be doing more harm than good.
Hope y'all like this idea :)