This is an original theme for the IceWM stacking window manager for GNU+Linux/BSD Operating systems created by us. It is a dark-purple-based, analogous theme for IceWM based on the included wallpaper.
Download and unzip, or clone the repo into your IceWM folder either located at /usr/share/icewm/themes or ~/.config/icewm/themes. Once installed, you can change your theme by clicking on the taskbar menu button and navigating to Settings>Themes>Nebula-IceWM or Settings>Themes>N>Nebula-IceWM.