How do you get free moba coins

When you are booting up zombie farm, its asks you to download other moba games and offers free moba coin once you log into that game with your same gamer login that you use for zombie farm. Once you login and the coin is added to you zombie farm acct which you can check by clicking the face in the upper right hand corner and then mymobacoin at the bottom left of the next screen. once you see that your coin has been added, you can then even delete the game from your phone but still keep the coin.
I used my coin first then deleted the game just to be sure but then the next time i deleted the game and the coin stayed. there are offers from 25-100 moba coin for these games. i tend to shy away from the 25's but the 50's and 100's i definitely download and get my free coins. by doing this i've already bought two monoliths, the no pay to plow and the speed farming actions, this allows you to make a lot more money on crops and it takes away the progress bar on all farming actions, soon as the farmer reaches the highlighted spot the action is done, pretty frickin awesome if you ask me. but as you get higher and higher in lvl's, i'm at lvl 30 right now, you seen to get less brains from invasions so i would highly recommend downloading the games for the free coin. and i just needed 3 brains to get my farming action monolith but if i would've waited for 200 more I could've gotten the next one up where you buy 5 and get 1 for free. I think that's the best way to go about it, save up and get that extra brain. Update as of 7-1-2013:

Now, this little trick still works, but the games are only worth 5-10 mobacoins each instead of 50 - 100. I've seen ONE 100 coin offer in three months.