Made with tmTheme Editor
To add this theme in the Rstudio list of themes you need to put the file in this directory (assuming the default installation path of Rstudio) C:\Program Files\RStudio\resources\themes
To add this theme in your Rstudio list of themes you need to put the file in this directory (this is from a Manjaro computer that installed Rstudio from the AUR so maybe with some other distros such as Fedora or Debian/Ubuntu derivatives the path may be different) /usr/lib64/rstudio/resources/themes/
Notice that you'll need superuser privileges to add or modify in this directory, so I recommend running cd /usr/lib64/rstudio/resources/themes/ and sudo wget https://raw.githubusercontent.com/enrique95/Rstudiotheme/master/synthwave.rstheme in the terminal
Pretty neat, huh? This pairs well with some Carpenter Brut or Perturbator in the background, or perhaps Blade Runner or Escape from New York in another window ;)