Dim the beatmaps you've already owned in game in the official osu! beatmap listing.
- Download the latest build in Releases.
- Start the executable you just downloaded. If it crashes immediately, you may need to specify the path to your Songs directory from the command line like
.\osu-bdi.exe --songs-dir "C:\Program Files (x86)\osu!\Songs"
. - Install the userscript from Greasy Fork or Github in your browser. A userscript manager such as Tampermonkey may be required.
- Open the beatmap listing and you should see the effects after the page loads.