This game has excellent replay value, and an enhanced version on mobile due to flash player limitations.
Some tips for you all:
-Towers cover the most path area when placed on or near corners.
-Avoid selling towers to avoid losing some of the money you put in.
-Placing a single block/barrier right in front of your base can help protect the door, and therefore your no-damage bonus.
-Sell factories at the end of a level to gain more gold for a bigger bonus.
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