Play HiveMC's BlockParty game with your own music
This program allows you to play BlockParty while listening to your own music. It automatically starts and stops your music during the game, allows you to use custom start and stop sounds instead of the cheer and vinyl scratch sound (although if you want to use those you can), and allows you to enable or disable the villager narration.
This program fakes sending the media play/pause keystroke on your keyboard to start and stop your music. Therefore, it should work with any media player that supports starting and stopping playback using this key.
Spotify has been tested and works. Sites such as YouTube and SoundCloud do work with Google Chrome - I haven't tested other browsers.
Sometimes an overlay appears in the top left corner when playback is started or stopped. To remove this, use HideVolumeOSD.
Head over to the releases page to download it. It's for Windows only, but it might work with Linux. I haven't tried.