Replay old campaign battles with upgraded units. Of course, the strategy for such a thing goes far deeper than that but be warned: This cheat is only possible after reaching a certain point in the game. To play on the safe side, don't try this until you're about Level 30.
By Joe Osborne From Games.com
1. Get the Goods
First things first, you'll need to get the equipment necessary for a trick like this work. Not to mention you'll need units that best match the battle you're looking to profit from. Brisson uses the example of grabbing at least three Sherman Tanks for the 7th Kai Tana battle in the Mercadia 1 series. Sherman Tanks require Level 26, cost 2,800 Coins, 140 Oil and seven Ore, and take 60 minutes to complete. Once you have these monsters, it's time to beef them up.
2. Better, Faster, Stronger
Once you've acquired your beefy units like the Sherman Tank (you can be creative if you like--just make sure it fits), it's time to give them the shot in the arm they need. So, head on over to the Army Research Lab and train the Sherman Tanks in Accuracy, which increases the chance of Critical Hits.
3. To Battle!
Now, it's time to try out your Sherman Tanks and blow up some planes. The 7th battle in the Mercadia 1 series features two fighter class Air units and two bomber class Air units. So, bring at least three of the Sherman Tanks along, and one pumped up unit to take care of the bombers. Even a basic, upgrade Cannon Artillery unit would do just fine.
Then, select the right targets and let the Critical Hits roll in, dropping all sorts of free resources and Energy to compensate for the Energy spent. Remember to have your Sherman Tanks and Cannon Artillery eventually upgraded to the max, because the lynch pin of this strategy is to lose as few units as possible in order to maximize your gains.
Rinse and repeat this until you have a load of new Oil, Wood, Ore, XP and Coins--and don't forget to keep that Bonus Bar going for extra Coins. Be sure to take advantage of this cheat before Zynga< catches eye, as some players believe it already has, though nothing has been confirmed.
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