Welcome to this William and Sly Walkthrough!
Click on the map to zoom in.
Color code for the map: Yellow = mushrooms ,Blue = chests ,Brown = switches ,Pink = monsters ,Red = Runestones ,Orange = Keys
Apologies for the map being hard to read, especially to the colorblind folk.
To get wings, which you will need to reach some areas, stand on the pedestal in the second temple for a about a minut
He will pass by either on the top, or on the bottom, with his mouth closed. That place will be safe when he passes by the next time with his mouth open. After he passes by go back to the middle and see where he is going with his mouth closed the next time and go there.
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