War Play:
First, the war period is way too short. You should be able to collect war items at any time. It is very difficult to collect needed items in the preparation period, especially if you have cards that require multiple war items. I would suggest making war longer and fewer items required to activate cards.
Second, you need more information on gaining new cards and leveling up existing cards. I have several cards I cannot use for some reason and several that I would like to level up but am unable to do so. I really don't understand how I can get the cards I would like.
Third, make it worthwhile to win the war. The rewards are pathetic, and not much different if you win or lose.
Finally, allow a club to determine if they will be a war club or not. If the club opts out, they will not be attacked, but they will not get any war rewards.
In reality, warmongering generates a lot of profit and different industries. Go back to the roots of Simcity and engage more realistic simulations. This has turned into a not so realistically simulated city building game and you have added a war feature to try and build competition. Nice try but not really effectively executed.