OSDev.org

Looking for Vitruvian man pictures, I stumbled across this page. Home page of a game made in Visual Basic. So I thought I'd give it a try. The demo isn't realy that interesting, but when I quit the game, I noticed the folder icon of the folder in which I installed the game was changed. I think it's a really cool effect and I was wondering how he did it. Two (invisible) files were created in the folder: gladfold.ico (which is the icon he used, a green folder) and desktop.ini. This is inside desktop.ini:
Copy-pasting these files into another folder won't work. Any idea how this works?

desktop.ini must have the system and hidden attributes; e.g. run attrib +s +h desktop.ini

Alternatively, folders have a "Customize This Folder" option on the right-click menu, where you can change the icon.