Can someone please tell me what sorcery this is? (or rather, where in the *** this custom world is stored, so that my game keeps recognizing it?)

As stated, I removed my entire Sims3 folder and let the game create a new one, because I wanted to have a vanilla game for building purposes. Yet when I load my game, my previously installed custom world is still there! How??

Thanks for any insight

Edit: never mind, I found it in C:\Program Files (x86)\Electronic Arts\The Sims 3\GameData\Shared\NonPackaged\Worlds

Well I'll be... Is that new? I wish I'd known this before my last rage-uninstall...

That was the workaround we used during the Seasons mockup by EA. Perhaps you put it there then?

That might be it, hehe
It's been nearly a year since I last got into worldbuilding