Yeah, there's already a lot of good points mentioned by others. This game has the potential to turn into an interesting strategy game, with the ball-and-chain mechanic being notably unique, but there are just so many minor annoyances, it almost seems like you *want* to make the player rage-quit. I'll sort them by how annoying I found them to deal with while playing.
Pain Point #1: Area of View
There are so many times I ran into a situation where I only realized I was doomed after taking a few steps, but there was nothing I could do about it. I know this may sound a lot, but when I can roll up to a 6 and guards can roll up to a 6, I feel like I should be able to see at least 12 tiles in any direction. That doesn't necessarily mean this needs to be the default area of view, but at least give the player the option to zoom / pan the camera so they can see that far.
If you want to keep a bit more of the cramped prison atmosphere, you can think about adding a line of sight algorithm that hides tiles that are blocked by walls, or maybe grays them out if they have been previously explored, but are not currently visible. Sort of like old strategy games like Age of Empires.
Also, bonus pain point: I only realized on my second try the area of view was actually bigger in full screen. I don't think that's something that should happen.
Pain Point #2: Slow Guards
I absolutely second what Szym said about this. Why isn't the guards' speed much higher by default? This is not a power-up, this is a convenience feature! Ideally, guard speed should be a setting that can be adjusted to the player's preference, but yeah, I don't think you can go very wrong by just setting it pretty high as a default. As long people can follow the guards' movement visually, it should be fine.
Bonus nitpick: The music change is just soo jarring. Maybe think about adding a cross-fade there.
Pain Point #3: Too Few Ways to Counteract Bad RNG
I originally wanted to say this game is too random, but on further inspection, that's not the problem. Slay the Spire is a very random card game, but one of my favourite games of all time! And you're already doing the right thing by using input randomness instead of output randomness. So, why does the game still feel so random?
I think the main problem is that oftentimes, there's just not much you can do to counteract a bad roll. Trying to sneak behind a guard in a 1-tile corridor but rolled a 6? Tough luck, no choice but to run into them.
Adding more dice and keeping them as backup numbers is a very nice start, but it's introduced at a point of the game where I believe you might have already lost the interest of a lot of players, so I would do that much earlier. I'd also like to see a simplified dice selection method, maybe just click on the one you want to use or something.
Pain Point #4: Unnecessary Guard Turns in Safe Areas
I would mark certain areas of the game as save zones. As soon as the dog enters them, the turn-based system is paused and you can move freely until you leave the zone again. Admittelty, there's not a lot of safe spots in the prison, but when I have to move through one at a excruciatingly slow pace of 1 pip per turn, I do get a little annoyed.
Pain Point #5: Counting is Annoying
I don't want to spend every turn thinking a long time about where I can go and where the guards will go. I would love a few UI improvements to help with that.
A very simple thing that I love in puzzle and strategy games that require any sort of counting is using a checkerboard floor. Not only does it make counting easier, it also helps with quickly evaluating the parity of entities.
If you want to be even nicer to the player, you could think about adding (optional) path markers for the guards' intended movement, assuming they don't run into dynamic obstacles. Also, you could mark the squares that the player can end up on given their current die. This doesn't really give the player information they can't figure out on their own and unless the process of figuring things out is interesting in itself (which I don't think it is here), I'm always a big fan of giving the player the available information in the most digestible form.
Some More Suggestions That Didn't Fit Into the Format
I would consider switching to a completely mouse-based movement system. Click the dog and drag a path to wherever you want to go. Backtrack to the dog to cancel movement.
The graphics are cute, but a little jarring. I think the main problem is that the contrast between background tiles and sprites is too low. Increasing that contrast might already help a lot, for example by brightening / desaturating floor tiles.
Sorry If this sounds overly negative. Again, this is a game that I think has potential and is mostly dragged down by a bad user experience, but if you put some time into fixing the main annoyances pointed out by the people here, this could turn out to be pretty fun!
EDIT: One little thing I really wanted to mention because it stood out for me but totally forgot: Having the sound effect match the number shown on the rolled die is a great touch! I love it!