This is a port of the beautiful VSCode Horizon theme by jolaleye for JetBrains IDEAs. The syntax theme is a slightly adjusted version of the theme by xShivan. The UI theme was written by myself.
To install download the .jar file here. Then import it in your JetBrains IDEA (Settings > Plugins > Install Plugin from Disk...). Now you should be able to select Horizon from the Theme dropdown list.