Our browser-based game development software Construct commonly saves user projects to a .C3p file. However that is really just a ZIP file containing a folder pr...
The 0 byte ZIP thing happened to me twice in 5 years and my bacon was immediately saved both times, because I store all my Construct projects in a folder that is inside my Dropbox (and I'm almost always online). Dropbox keeps previous versions of files in the cloud, which also came handy a few times when I've accidentally saved or overwritten the wrong file.