Here's how to get all medals and only play adventure mode once
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The worst part of this game would have to be the thought of playing through adventure mode three times in order to get bronze, silver, and gold medals. Here's what to do to only have to play adventure mode once:
Play through the entire adventure mode on simulation difficulty. After getting all the gold medals for this, go to Open Season mode. In Open Season mode set the difficulty to one of the lower levels and then play a level. After completing the level you will get the achievement for whatever difficulty you played it on for whatever part of Alaska that level would be under.
For example:
If you played in Open Season on the North Slope level on Greenhorn difficulty you would get the Western Arctic Bronze Badge.
If you played Sitka level on Sportsman difficulty you would get the Southeastern Silver Badge.