What is the crowd's opinion of opsu!?

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Sort of, I play opsu! an open source osu! client that runs on linux (I would play on windows, but I only have Linux boxes atm). I've only played original osu! a little bit, but opsu! seems to be a pretty faithful implementation except it's much harder to fail a beatmap. A hear osu! is going open source soon, so a linux port should be coming soon.

If you want to play osu!, use the open-source replacement opsu!, which runs natively on Linux (as well as on Windows, macOS, and Android).

The official client has some, uh, serious issues.

You could try installing it though lutris if you want to use the official client

or you can try opsu! an unofficial client with native Linux support which you can also install though lutris.

Not at this moment because of pain, but opsu! (osu! but with an unofficial APK). The high amount of mouse acceleration in Chrome OS makes it pretty tricky to play as well.

There's an open source, cross-platform OSU clone called opsu, haven't played either though so I can't tell you if it's good or not.

For all your windows-specific programs, I'd recommend finding some Linux compatible alternatives for them, and get used to those before switching to Linux. That way, it's less of a jump, and you're already used to some aspects which otherwise would be different to you.