I love this game, but I have a real problem with the contracts. Not how hard they are, but that they must be done in one day. For example, one of the contracts is to kill 30 with a long shot on the bridge map. The actual contract is not that hard, but completing it in one day is very difficult. The bridge map is not very popular, so it's very possible that you could do 29 long shots and then no one plays on that map for the rest of the day. And gold contracts can take most of a day to complete. This prevent anyone who can only play this game for an hour or a two a day from ever being able to advance far in the contracts, not matter how skilled they may be.
I think that maybe it would be better if you made the contracts harder, like 100 long shots on the bridge map instead of 30, but allow your progress to be saved at the end of the day. I really wish that you could make this change, because to be honest, everyone has a point where they just completely give up on their contracts.