I know it's only a small team and I have no idea if it is a lot of work.......
But it's 8th November and already RaaRaa is yearning for the christmas trees. She is so, so happy, we got Tundra :)
So, with her heartfelt encouragement, I would like to suggest the following:-
A mini quest, with christmas themed stuff, give away resources (play Santa/father christmas), visit a friend, to party (reinforcing), host a party (recieve reinforcements), plunder resources (be the grinch), etc. Rewards could be the usual stuff, plus maybe some "good neighbour packages" to give away. Last reward could be a statue, of a christmas tree, but in colour.
A Christmas Tree(s) in the build menu. Like the statues, it would not need to have population or culture, just be a decoration. Other buildable decorations.
Maybe put some christmas outfit items, in the cash shop. It used to sell outfit items. I really miss my pumpkin hat, I would definately buy that.
For the future, maybe other seasonal stuff, or some mini themed quest tree, every few months, or once a continent.