One of the most interesting games I've seen here so far, reminds me of Verlet Swing. A better to stall yourself in the air to have time to move your cursor to the next ball would be highly appreciated since it is hard to be precise enough and fast enough to not overshoot the balls. Having double jumps decrease or outright remove your current horizontal distance like car breaks would help tremendously, as well as decreasing the gravity on the player and making them accelerate slower and/or decelerate faster after dashing at a ball to make chaining dashes between red balls easier. It might also be better to make it so the player cannot collide with the red balls, as it rather kills the flow of movement to suddenly halt when bumping into them, when one wouldn't naturally expect that to happen instinctively. Maybe hitting a red ball could trigger a dash, just like slashing them, so the player can chain through the red balls without having to continuously click for every ball? This automatic dash could grant the player less speed than a manual one from clicking the mouse perhaps, so players would have the option to try to manually hit all dashes to clear levels faster.
Overall, I love this prototype! I would love to play an actual level of this game, and it seems very well fit for speedrunning and trying to beat levels as quickly as possible or without hitting the ground.