I am running Arch Linux with i3wm. I have customized i3 a lot already, but I also wanted to try transparency in urxvt. The pseudo-transparency does work, but when I try real transparency, instead of making the terminal transparent, it just becomes darker.
In my .Xdefaults file I have:
urxvt.depth: 32
urxvt.background: [75]#0e192e
urxvt.cursorcolor: #ffffff
urxvt.foreground: #ffffff
I have removed all the pseudo transparency stuff like urxvt.transparency and urxvt.shading.
In my ~/.config/i3/config file I use exec_always --no-startup-id feh --randomize --bg-fill ~/wallpapers/* to set the wallpaper.
I think it's likely that it has something to do with the wallpaper.
one solution would be to use Compton compositor - https://wiki.archlinux.org/index.php/compton