There should be like a reward for loging-on days in a row. Like the 1st day you get 50g, 2nd 150g and so on , and when you get to 7 days you get an extra present that could be a random amount of gralats/items. If you miss a day it restarts, if you get on for 7 days it restarts too.
There could also be a to-do list everyday, you have to do for example 3 tasks that day and if you complete them you get a reward.
I suggested on another board that maybe when there is Rambo in the city there could be things broken and you need to fix them with a tool (same tool as ship repairing) and earn gralats.