For the MZ games (Mobile Strike and Game of War), every time you log in you are immediately taken to a full screen "buy" page wanting you to buy gold packs. Your first one is $4.99. If you actually buy that, then the next one you can buy is $19.99. You can't go back to the lower cost pack, though there is a $9.99 pack if you hunt around enough. After a few of those, your only option is the $99.99 packs. I blew $5 on the first pack way back just to try it, never again.
Then, once you log into the game, you're presented with at least three spots on the game screen asking you to "buy gold", as well as the option to use gold to speed up virtually every thing you do. Incentives are all over such as daily gold bonuses, extra build and research queues, etc. Then, you can't do squat in the game if you are low level once your kingdom (GoW) or state (MS) get mature. By this point you're dealing with massively strong individuals, strong alliances, and people who spend $100's per month on more and more packs to stay ahead. You'll always be a little guy unless you fork over big loads of cash. If you get into a good alliance, you'll get lots of gifts and resources from the big guys who want to help grow the alliance, but you'll basically never be strong enough to compete. The gifts will only get you so far, power comes through spending.
