ScreenPlay is described as 'Open Source cross-platform app for displaying Video Wallpaper & Widgets. It is written in modern C++20/Qt6/QML. It currently supports Windows and macOS (x64 and arm)' and is a Wallpapers Hub in the photos & graphics category. There are more than 50 alternatives to ScreenPlay for a variety of platforms, including Windows, Mac, Linux, Android and F-Droid apps. The best ScreenPlay alternative is Wallpaper Engine. It's not free, so if you're looking for a free alternative, you could try Lively Wallpaper or Paperize. Other great apps like ScreenPlay are Wallper, Wallspace, Sucrose Wallpaper Engine and Variety Wallpaper Changer.
ScreenPlay is very close concept-wise to Wallpaper Engine though it has several other features beyond just wallpaper. It lacks the complex wallpaper maker Wallpaper Engine has but the script based focus is very easy for coders and it has the benefit of automatically being cross-platform for Mac, Windows and Linux.