Zombies!!! XXX

 

Using the roman numeral for 30, you can't help but think what this expansion would include. But I would keep things R rated and just go for new player figures (all woman) and add in my city tiles but with these special strips called "back alleys" which allow you to take short cuts through the town by going inbetween buildings on tiles. 

This would make the game go a little faster and help others who end up on the wrong side of town after all the tiles are placed. The cards will feature "girl power" and I think female fans of the game would appreciate that. 

I'd also create a few 3D building stand ups so that you can have battles on the rooftops as well, which would give the expansion a special impact that every 10th one should.