Great Game! Short but sweet, short enough to make me want to squeeze out my own version of 100% (all possible upgrades for one day). Through that i've discovered a peculiar bug.
First of all, by sticking all the stamps on one of the packages in my shed, i get to keep over all my stamps. The fee for keeping one package in my shed is totally fine compared to worrying about having the correct amount of stamps.
However, to my annoyance, and this is the bug part, when unsticking a stamp, it is not treated as a stamp to the stamp sorter. This is resolved, eventually, when you get the poster. By sticking them on the book, then unsticking them, they become real stamps.
An annoyance to be sure. But much less annoying then doing my own stacks. An appropriate punishment to cheesing the game, but it would still be pretty confusing and frustrating to a casual player.
Oh, and the poster itself is *really* finicky. Sometimes i can't go near another stamp, and then a bit of finangling later i get to place it there anyway. I'd recommend grid-locking it, or at least giving the option to do so