For 29 I didnt realize you could hit a button again to 'unpush' it. So you need to use the big ball and push the button as it falls. Now Im stuck on 31. Always like a second short.
Just for fun I fought with an all (but 1) archer army in a custom scenario. Worked out pretty well - killed 5k of their troops, and only lost 900. The bridge map let me line up 4 archers in each line cut most of them down before they got to my duke/infranty troop that blocked the bridge.
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 "Factory Balls 3"){kind=icon}
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 "Epic War 3"){kind=icon}
 "1066"){kind=icon}