Incentives for more activity

   Our genre usually does this vastly different ways, one of them is to have a weekly challenge.
It could run for many different things, but since we don't want to solely be a war-game, I was thinking you could give points for in-game activity, (either hidden, so we don't know exactly what will give the points, or show what you have to do to achieve it.

It could have certain stages, each giving you some more unique stuff if reached.
Crude example: when you reach activity points 2k/4k/6k/8k/10 you are able to open a gift, containing the incentives.