Edited: Thought of some stuff about scoring systems and a beat-streak
Voiceless has pretty nice art, and the gameplay is using some interesting ideas. There's some good potential in this game if you want to keep working on it, but I do think it has some kinks and issues to work out.
I think this game is very charming, the presentation is very good. One of its biggest strengths. (Also, pretty much the entire thing from this point on is going to be criticism, so I want to make extra clear that I do like this game. It's super interesting.) However, the gameplay needs tweaking. The main issues holding it back are the controls, which feel difficult to get ahold of, and the overall experience could be improved if the level-design philosophy shifted to one about keeping momentum, rather than careful platforming, to mesh better with the beat-gameplay.
Summary of my suggestions:
-Add a beat-keep key (a button that registers the beat without jumping or dashing), to make staying on beat possible without requiring movement
-Show more yellow beat circles at a time (maybe 2 or more circle scrolling total, or have the entire bottom screen show the circles scrolling past), to make is easier to see upcoming beats
-Make the jump a consistent height instead of based on how long the key is pressed, which avoids accidental short hops that tend to occur when you're trying to press buttons onto the beat
Opinion suggestions:
-Shift the level design from dodging death-obstacles to movement-obstacles (challenge coming from moving forward rather than avoiding death)
-Focus on level design that emphasizes keeping momentum rather than carefully avoiding obstacles (less stop-and-go sorts of situations)
-If the focus is shifted to keeping momentum, adding in a score based on a beat streak, or adding in a level timer, can be great ways to encourage the momentum gameplay, and gives you some options on obstacles where the challenge comes from keeping pace rather than just plain getting through
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Details on each point:
The rhythm-based movement should be leaned into a bit more. At the moment, it feels like you walk in a normal platformer, but need to adapt to the beat in order to jump and progress. You stop walking before spikes, get a feel for the beat, then try and jump over them. This feels really awkward since, at the moment, there's not really a button you can press that isn't moving you to keep yourself on the beat the whole time. If you had an extra button (maybe the C key) that would register a beat press but otherwise doesn't do anything, it'd be a lot easier to keep your beat going instead of needing to stop to adapt to the beat once you need to platform.
Also, the yellow circle beat-key at the bottom feels too short. A circle or two to see the beat doesn't give a lot of visual feedback to get a feel for the beat. I'd recommend having a few more circles scroll by, or even just having the entire bottom screen with the circles scrolling by. Having more circles to look at for tracking the beat would help with getting the beat down. Having only a couple circles makes it difficult to track the next beats.
In addition, the jump having variable timing based on how long you press the button doesn't work with this control system. Needing to hold the button for a full jump makes it harder to press jump again for another jump, or transitioning into a dash, while all staying on beat. Having a consistent height on the jump would make jumping overall feel smoother, and prevent accidental short-hops from trying to keep the beat. You'd only need to worry about pressing the jump button, and not how long you pressed it. One less thing to worry about.
And lastly, this is more of an opinion, but I feel the level design isn't the best fit for the control style. As of now, the design feels very traditional for platformers, jumping between spikes and obstacles. However, I think a more enjoyable level design would be more obstacle-based instead of death-based, where the challenge is making it past barriers, walls, holes, etc. instead of dodging things that kill you like spikes and bottomless pits. The moments when I was able to jump and dash forward quickly felt the most enjoyable, and leaning into that with longer levels where you can keep momentum may go a long way to making an overall super fun game. The spike and pit obstacles didn't feel super great, especially since the controls as of now are hard to get a handle of. It felt very stop-and-go, which doesn't mesh super well with keeping a beat.
As an extra suggestion, if you do shift focus to more momentum-based gameplay, a beat score could go a long way for encouraging that type of gameplay. Emphasizing keeping the beat going with a score would add an extra dimension to the gameplay, and actually would give you more tools to work with level-design wise. A score would give specific purpose to obstacle design where the challenge isn't just to get past, but also to get through efficiently. For example, say you drop down a hole, and the way forward is through a hole in the wall above the ground. Just landing at the bottom and jumping through would be fine enough to progress, but to progress while keeping a better score/speed, it'd be more beneficial to dash through midair, keeping your speed.
These level-design bits are subjective though, these parts are up to you if you want to pursue it.
Overall, if the controls were tweaked a bit, I'd definitely give an extra half-star or two. If the level were designed a bit more horizontal, with less emphasis spikes and more on moving past blockages and obstacles, I'd definitely give a full 5 stars. The presentation already is very nice, and the gameplay has a good foundation that just needs some refining.