Hello and welcome to Feedback Quest 9! My name is Hythrain, and I'm one of the hosts for this lovely event! I'm also one of the streamers, so both the game and this feedback are being done live! If you want to see the see the VOD, let me know and I'll link you to it when it's uploaded to YouTube!
Normally when I play a game, I write notes down for when I get to the feedback part. However, I was having so much fun that I just didn't write anything I was thinking about down. This isn't to say there isn't feedback, just that the gameplay is so enjoyable that I didn't want to stop going.
The first thing that came to mind, which was first mentioned in my chat and which I agreed with, was the look of the lava. To me, it just looks like red water with a yellow surface. I'd love for the lava to have a more lava look. I also felt that overall the visuals were lacking. I'd love to see that improved as the game gets polished.
I noted how when you're moving through the air and grab a block from above, it can stop your momentum. I don't think this is a bad thing. I'm really glad it does this, especially when I did Falling. However, I'm unsure if this is your intent so I figured I'd mention it in case it wasn't. Again, I think it's fine and should stay!
Based on the game's design, I can't refer to any of the jumps in this as "blind jumps" since most of the time they require you to be swinging anyway. However, I did feel like some jumps were too difficult for when they're presented. For example, the long jump in... well, Long Jump. I found it required me to be going a specific speed and to jump at a very specific angle. Since it seems that jumping during a swing can lose some momentum, I kept feeling like I needed to start my swinging from a very specific point in the block. I'd love to see it that when doing any jump, you can have your grapple on any part of the block you're using and that there's some more leeway in your angle for launching. With regards to momentum, I think needing specific speeds is fine.
I noted that with some blocks, you would only get a certain amount of room to extend out due to either other blocks or terrain. While this is fine when you have a series of blocks in a short distance, as seen in Falling, I feel like in some place it's more problematic as you need bigger swings and more momentum to make progress. Since I didn't write things down, I can't recall which levels had this. I'd overall say that unless doing a series of blocks in a short distance, it should always be possible to get max distance on the rope even if it isn't needed.
I'll also admit, I got to Rising but I just found it really hard, especially compared to Endless. Maybe it's because I didn't understand how much vertical momentum I actually needed and kept assuming I needed more, but I struggled to get to the 350m mark you set as the first (chaos) emerald. I think what would be more interesting is if the blocks (which should also be in set positions rather than random each run) went further out more but not as high, then have the lava just rise slower (and not gain speed). That way, you can make the jumps with less vertical momentum. This could also then be fun for people who are more skilled at the game as they could skip some blocks by making more use of the vertical momentum. Lastly, as you progress higher up the jumps would become harder and harder, each block being higher but getting closer in terms of horizontal distance so you were relying more on vertical momentum.
Speaking of emeralds, I'd like to suggest that the emeralds you have to find be saved once you find them, even if you fail the level. Many levels have speed requirements to get all emeralds, and taking the time to find those emeralds means you'll likely not make the time. If you want to make it that you have to get these emeralds and make it to the goal in time to save all emeralds, I'd then also suggest giving more leeway to the timed aspect. For context, I felt this particularly in Falling where I didn't even bother going for the hidden emerald and it took me over 60 seconds to reach the end because of that one part of the level where you have to go relatively straight down but you can't see where you're going unless you extend out. If I had to get that hidden emerald first and THEN beat the level in (I think) 47 seconds, I'd never manage it.
All of this said, there was one major problem I felt I had: trying to grab some blocks. There was an instance where I was fairly confident I had hit the block with the grapple, but it just didn't grab and instead I fell to my death. There were also times, particularly during Falling, where I would attempt to grapple something and the grapple would overshoot a block but the rope would pass through it. I'd like to see it that the grapple has more leeway to ensure that so long as the graphic for the grapple touches a block (even if the main hit detection part doesn't), it's able to grab in a forced grab way. I'd also like to suggest a special Easy Mode function where, if your rope passes through a block, the grapple will then grab that block as well based on the closest point of the rope to the player that touches the block. You could even add an extra emerald in very specific stages (like Falling) for not using Easy Mode, but only display these emeralds if the player completes the level without using Easy Mode. That way, players who use Easy Mode won't even know these exist and won't feel punished for using it.
In terms of suggestions to expand the gameplay, I have a few ideas. First I think moving platforms and blocks could be interesting. This would, of course, really necessitate the idea above of making the grapple have an easier time grabbing blocks since grabbing a moving block could be challenging if the block is moving away from the player.
Another thing that I think could be helpful, which may be challenging to put in, are blocks that change in dimensions once you grab them. Right now, all of the blocks you can grab are just that: square blocks. However, one thing that could be useful for the player (and which could help with some of those sizing things I mentioned before) would be if some blocks (not all) would shift their dimensions when you grab them in certain spots. For example, if a block wants you to stand on it or grab from the bottom, perhaps once you're doing this it can shrink the sides to make it that the top and bottom are the more accessible parts. In this way, you can even indicate to the player what's the ideal way to grab the block as they're learning the levels. Again, this could be challenging to put in. It'd have to be done very careful to prevent hit detection problems. However, it could also be a useful learning tool for new players. Heck, this could even be part of that Easy Mode idea, meant to help teach the player how the levels work better so that they can more easily tackle them outside of Easy Mode.
I think that's all I can think of! This is honestly really fun, and if I get the chance I'm going to try and get better at it to get all them (chaos) emeralds.