For a game online like this. all of player like to be online as long as possible, but none want to other player do it all the days and 24h/24h online always! There’s a great idea for this!
Give everyone a possiblity to attack the player online. We can sent a challenge when the player is online. It could be spent gems or more foods. And needs some limit of times could be invited. Or the player always online will get crazy~ The challenge can be active only keep online more than 3h, in this way no take too much trouble to a normal player!