https://bugs.winehq.org/show_bug.cgi?id=44184
--- Comment #3 from Invictus Tiberius invictustiberius@gmail.com --- (In reply to reduxpl from comment #2)
Thank you for the response. I do have .NET 4.5 installed (with winetricks), and I do run Wine version 3.0-rc1.
Tried again on a new wine prefix. The same behavior you describe happens to me.
When osu! starts, it checks that all required files exist in its directory. But for some reason, the file "discord-rcp.dll" is never copied to the main directory after been downloaded by the installer. So osu! downloads that file again and again. This may be related to a bug in osu! itself: it gets updated indefinitely.
However, I just found an easy workaround: create a dummy "discord-rcp.dll" file directly on the osu! folder. osu! will start normally and probably it will try to update but you will be able to use the game as usual.