Eastward

It is self explanatory, but just some info for people that may be worried about it: yes it includes the pan that you receive at the end, yes it is doable with chapter select after the ending.

So let's say you are doing a second playthrough for treasures hunt, and probably by Monkollywood or Island of Time you have your treasures achievement. No you don't need to do all the rest of the game.

Just select the last selectable chapter and section (you will have for sure the pan at the highest level) with your improved gear thanks to having found all the treasures, and the achievement will pop.

Also there are no extras gears: if you are missing one or more, you are also missing some treasures.