I usually don't like to make reviews anymore, but after seeing BerzerkStudio constantly say "Play the multi-player, you get more gold that way," whenever anyone brings up a complaint/critic about starving for gold...Then boy, do I have something to say.
If this game is designed with an online multi-player that also includes an alternative reward system for the player to reap, then why bother having a single-player/offline mode where there's -no- other alternative reward system other than grinding missions for 200 gold or paying real cash for gold? To me this seems like bullshit.
Don't get me wrong, I get it. I understand your original intentions, BerzerkStudio, but you can't simply tell a person to switch over to the online mode if they come across a road block relating to gold or the like. It only makes the offline/single-player mode seem all the more pointless. In fact, it makes it feel like the tacked-on-mode, when it should really be the other way around with multiplayer mode.
As for "You can beat the Offline mode with the rewards you get from previous missions," I also call bullshit, since it ultimately comes down to how lucky you are with card boosters. Once you get unlucky on the cards you get, have fun grinding up for gold.
Overall, you made a solid game, but you placed too much focus on the multi-player functionality over the single-player functionality. This game probably would have gotten 4+ stars from me if there was only an online mode or if the features in multi-player mode were also included in the offline mode.