Very, very nice game. On to the topics:

UI

I find it really impressive, I love the tickets as buttons and how it all works together. The only points I got on this one are:

• In the settings menu, when seeing the cheats/interface, I thought the white font was a bit hard to see, maybe because it was smaller.
• I feel the background during gameplay doesn't blend in with the UI/3D elements. But I'm not sure what bothers me in it.

Obstacles

I really like the ones implemented, though I found the inverted dice harder than in the old version. But it might be because I was already used to the "sum to 7". Something I'd like to see, in levels ahead, was something tied to time. Like dice that turn around after x seconds or simply become disabled after an amount of time, so player can't get away with just swiping them up over and over.

Also, I really like the bombs now, they aren't so big and they always seem "swipable", instead of the angles they were thrown in the old version! I hit them twice in my run.

Player feedback

I felt like the dialogs before each stage were enough and it is easy to understand failure/success conditions. I just didn't get the logic of the star ratings, when I hit 3 correct out of 5 I still got 2 stars, does that mean as long as I get at least one I am passing? Also, something very minor I noticed, once the bomb exploded I had the retry menu showing up, but the dice that was rolling kept on going and entered the bucket, thus making the success sound effect. It's really no big deal, but maybe once the player loses you could stop the dice rolling or its sound effects?

Difficulty

I really liked the ramp on difficulty. It starts super easy but soon you need to be paying attention, and the inverted dice to me got quite challenging. In some of the later levels though, I think it became a bit overkill, perhaps you could start with stages that mix many ideas (buckets, bombs and 5 dice) with a slower dice spawn?

Would you play this if it were ad supported on mobile?

Not really as I ain't a mobile player.

First of all, this is without a doubt a very well polished and fun game! Since you're probably here for constructive feedback, I'll focus a bit on the things that can still be improved, but just be aware that those are mostly nitpicks and most of what you've done already works very well.

To answer your last question first, no, I personally probably wouldn't play this with ad support on mobile, but that's mostly because I'm just not a huge fan of mobile gaming in general and it's also not quite my genre, so don't give too much on that. It definitely has enough quality that I could imagine it doing pretty well on mobile platforms. Just be sure not to overdo the ads and have an option to remove them entirely for a small fee.

(I kinda wish more mobile games would just charge up front, but I know that's not how the market works. Possibly one of the reasons why I dislike it as much as I do)

I have only one big complaint with the main game mode, which is that cannons shooting from the bottom obscure one of the dice down there. I often found myself rejuggling a die because I didn't remember what I was aiming for, and frankly, that's also not something I should be expected to do in this sort of game.

Other than that, this mode feels very nice! There were a few difficulty spikes whenever there were five dice to juggle, but those are fine. It's a bit annoying that the difficulty of those levels depend so much on whether you manage to get good rolls on your first swipe. I know I can influence those a bit in theory, but let's be honest, most people will just do a diagonal up swipe into one of the buckets here.

Also, maybe this mode is a bit short, but I'm not sure what's the best way to add more levels while staying varied. Maybe you can think of a couple more game elements you can add?

The new modes feel a lot like an afterthought. Practice mode just feels very weird and quickly slapped together. I'd like to be able to adjust the number and type of dice, toggle cannons, and so on for some actual practice. Maybe a simple solution would just be to use the default levels, but remove the win / loss conditions.

Endless mode feels like it could be fun, but boy, even at the very start it's just so much more difficult then the main mode! I'm not sure if there is such a thing as I only managed to get a score of 9, but if not, this definitely needs some sort of difficulty progression. Simple suggestion: Start with dice coming out very slowly and increase this rate continuously until theres more or less one constant stream of dice in the end. Also, maybe turn on inverted dice and cannons after certain score thresholds.

EDIT: Oh, and one more thing concerning endless mode, I'm pretty sure I would prefer if solved dice would be replaced immediately. Would also help lower the difficulty a bit.

UI, as well as generally the look and feel of the game are very nice. One suggestion I have here would be to add an outline shader to your 3D scene, which I think would help the 3D objects blend in better with the rest of the cartoonish style. Never tried implementing one myself and I've never used Unity, but here's a tutorial that seems to implement something similar: https://roystan.net/articles/outline-shader

Sound design is generally very nice, though I think the cannon shots could have a slightly more impactful sound. Music feels very synthetic, maybe there are versions of the music out there that feel a little more natural? I think I would prefer those.

Anyway, as mentioned in the beginning, these are mostly nitpicks. Overall, this is a very polished and professional-looking game, very well done!

So firstly, I was trying to get this to play on my iPhone because I saw it was vertical, but Unity's telling me WebGL doesn't support mobile and has a runtime exception if I try to get it to work anyway.

I think what's really great in the game is its progression of levels. It starts simple, but slowly introduces more and more mechanics with each level, increasing the complexity in a manageable way. Reminds me of the way Portal is designed, where the first two-thirds of the game is a tutorial, yet it doesn't feel like one. 

I like the whole inverted dice mechanic too because you're then not just trying to juggle the dice but juggle which way they're supposed to be filled-in in your brain. I also like how the goal dice match the regular dice while the inverteds don't match. I saw in the original screenshots there originally were numbered dice, and it's good that it was changed to this shape filled unfilled system. Also it was a good choice to have the dice be fixed in orientation after you slash them -- it would have been so finicky and annoying if they retained angular momentum.

I thought it was interesting playing the original though that the change to vert didn't even seem like it affected gameplay that much -- it didn't necessarily seem any easier, so I think that's a good thing -- the orientation change didn't mess with the design. The ball dropper though is a great addition -- it looks better than the timer and the way it rotates before it drops gives the player some notice about the incoming die -- plus since you can see what die will fall ahead of time it lets you plan a little bit, as opposed to it just spawning.

I also thought the star system was a great way to reward perfection without requiring it -- the original had to have you be perfect, but deluxe lets you move on anyway. Well OK you could just hit skip level in the original but I imagine most people would be much more resistant to pressing skip than to just continuing with 2 stars. Though it's maybe almost a little too forgiving -- you only need one die to match to move on, which probably would just happen if you did nothing. But if you had a skip level button anyway, what does it matter really?

I was kind of disappointed the last level didn't have me putting everything all together -- buckets, regular + inverted dice, and bombs (I think there weren't buckets). Just because it felt like it was building to me managing everything at once. But you could also now look at the whole game as a tutorial for endless mode. Yet endless mode doesn't even have the buckets -- though endless mode is much harder so I'm glad it didn't have them really (I didn't have too much difficulty throughout the levels, got 1 or 2 stars on a few levels, but immediately went back and replayed and got 3 stars. Never even hit a bomb until I decided to slash one intentionally just to see what would happen, and seeing as it immediately ended the round, I'm glad they weren't too difficult to avoid because that would've been frustrating).

Actually, while I think the levels and everything are designed great, I do wish there was a little more to endless mode. The dice drop super fast, getting you overwhelmed immediately, and when you clear a line you have to wait for the cup to drop more, meaning you have to continue juggling even as more drop out. I think maybe the dispenser should at least wait to start dispensing again until you can see the next dice goals -- you can keep juggling the ones you have of course. I appreciated that there was a cap of the number of dice allowed out at once, something like 5 or 6, because I was very quickly getting bogged down. I think endless should probably gradually increase in speed rather than it being fast immediately, or maybe difficulties levels for it. I maxed out at a score of like 12, which didn't seem very high of a score. Oh, also, there should be a display of how many mistakes you've made because otherwise you're making the player count to 3 themself.

As for aesthetics, I do really like the messages with their elephant watermark, and I had no problems with the UI. I kind of don't understand where I'm supposed to be -- the music tells me I'm at a circus, but I appear to be in some kind of shed with broken balloons on the wall? Is this like, a washed up clown's house/run-down cabin? 3d models are decent but could probably look a little better with some kind of shader/lighting/idk-im-not-an-artist, particularly on the dispenser and cup, which give off a kind of non-anti-aliased kind of vibe?

Would I play this as a mobile game? Well, I download like 1 mobile game per year probably, so not me personally, but I think it would be good as a free app with ads. You'd probably want to add a few more mechanics though, and then make endless mode a little more robust with an online leaderboard.

As for more mechanics, idk my brain thinks of a floating ring that's either colored and you have to hit a die of a certain color through it, or it's labeled with a goal die and it has to be in that orientation as it passes through. Maybe certain dice crumble after a certain number of hits (I'd be generous with it and allow it to take more than enough hits, but the challenge might be that you'd throw in regular dice with it too so you'd want to prioritize the crumbly dice first). Maybe barrels that move or are in different spots of the screen other than the left and right? Maybe add in a new item type, bowling pins, and you have to slash them mid-air like the dice but you need to make sure they land face up? Or maybe you have some kind of floaty ball that has a bomb inside and it'll explode once it hits the ground, so you have to manage that while orienting the dice (essentially like a die that's got to stay in the air, but probably more floaty than the other dice so it's not as frustrating to deal with).