Maybe add some long harder missions (stuff like weekly and monthly) as well as career stuff like "reach field marshall 3 times" which could give more diverse rewards and give more things to grind for. Certain career missions could be focused on playing "1000 soviet cards" or things like that. They could give cosmetic rewards to the specific country instead of giving 100 gold to someone who already has 1000+.
Also remove ambush mission pls.