The contract system is faulty; it may drop back to 0% after a game ended. It is extremely annoying to see that you complete 30% in a game then it drops back to 0% after the game...
The devs added daily gold bonus but the roulette became useless afterwards. I almost always get 1 or 2 "Nothing" every time... The devs are cheap, tweaking the probability like this...
 "Contract Wars"){kind=icon}
 "Take Something Literally"){kind=icon}