Use A/D and/or left/right to move around. Click to throw a cardioid boomerang. How far away you click matters. Try to hit the hearts with your boomerang, but make sure you throw it in a way that lets it return without hitting any obstacles! Press L to skip a level if you must.
Press M to toggle mute/unmute. The background music is Come and Baguette Me by Bezakos and 1C3: https://flat.io/score/64a58a2e719a2b9175ade5d7-come-and-baguette-me (Well it went through a lossy compression and has been cut into its main sections to sorta fit with the levels but still.) If using this music is a problem, I can get rid of the music blocks (but keep the link to it as recommended music or something and the general script (and preferably the mp3 cut into sections) maybe), although I'm not very active on Scratch nowadays. That being said, this is just a hackathon project... Sidenote: there may be a glitch that lets you get a heart with your last throw's "residue" if you make your current throw right after your last throw and your current throw doesn't hit an obstacle.
