Did you just open the zip file and open the game in there? You have to right click and extract the zip into a folder to properly play the game and save, otherwise all the game files including your saves are only temporarily extracted to a temp folder deep in your Windows user folder.
If you extracted 0.8.0 and saved your save files will be in the www/save folder, otherwise try looking in C:\Users\<username>\AppData\Local\Temp, but no guarantee they're still there.