https://github.com/guo-yong-zhi/ShuffleSS
Here is my approach. Unluckily, the description is in Chinese. To be brief, you should put your pictures into `/usr/share/blanket/screensaver`, and name them correctly. And a further file-name shuffle may be useful. You should be careful to edit the `/usr/share/blanket/screensaver`. It can be risky.