Idea for Clash of Clan Challenge
Okay, think of this. Some sort of disaster has happened, all the elixer pumps, gold mines, and dark elixer pumps have run dry for a week and you can't get any resources except from attacking, or buying resources. If you can't protect your base, you lose all of your resources and can't do anything for a week. Now, there's also a possibility of having to defeat some sort of boss goblin base to restore your pumps drills and mines to their former selves. I think this would be a really cool challenge, it would cause people to play more (and psst, Supercell, some people would have to buy resources with money).