Buy a game, install them, then download crackers to remove disc check / whatever stupid check it has, then I dont need disc to play the game. I picked most discs in cardboard boxes and put them away in storage room for years. Never quite motivated to maintain a library management for them.
D:/games/!storage for zips, .isos, install files, etc
D:/games/ for installed and unzipped games, then chuck a shortcut in that same directory.
Steam, GoG, Origin and ilk installed also in D:/games/
My desktop is completely clear, and psychologically it's so much nicer - just a giant lovely wallpaper image and a clean slate. Windows 7's "hit Windows key and type" is actually faster than anything else, for me, anyway. For games not in the registry I just open /games/ and use the shortcut. The Start Bar search is really, really, really useful.
My games are all over the place...
I have lots of physical dics based games , loads of stuff on steam, a few on gog , a few on that shitty origin service and a few on other DD services , several that have their own account systems (world of tanks etc) and a bunch of pirated stuff too.
I don't really organise tbh.
I have a few categories on steam to keep things easy to find because my list got too big, and a bunch of shortcuts on my desktop of stuff I still want to play/play that isn't on steam.
The desktop shortcuts are nice, my desktop may look really messy with all the icons and folders but it's nice to randomly notice a game that I haven't played in a while.
Not like there is any other use for the desktop space anyhow with Pin to taskbar and libraries in win7 or just typing in the first 3 letters in the start menu, it has just become a post it board for random stuff that I need to/want to be reminded of or never want to lose track of.
I bought an hard disk exclusive for games. I've got five folders. Steam, GOG.com, Desura, Retail and lastly Miscellaneous. I also have an encrypted database of all game purchases with links and product keys.