It's called "Strung", and here is the link: [https://s9menine.itch.io/strung]
You can play it in the browser, but you'll need to click on a "Run Audio Game" button first. The rest of the game requires keyboard only.
It's also available for download. To download the game, first click the "Download Now" button, then the link labeled "No thanks, just take me to the downloads". A new browser tab will open, then you can choose which version of the game (Windows, Linux, or Mac OSX) to download from there.
Hope you have fun, thanks!
P.S. Here's a short demonstration/walkthrough of the notes you can play, if you don't mind spoilers: [https://www.youtube.com/watch?v=tJSbmlqHdL8]