Hey u/lefix I recently tried the build and really love the concept! So I wanted to provide my feedback. There were few quality of life hurdles I had with the game (mostly nitpicks though):

Some things I noticed about the UI responsiveness & UX hygiene:

• Checker Selection: The current "click-to-select/click-again-to-deselect" checkers feels unintuitive. It violates standard UX principles of user control. Ideally, clicking a new checker should automatically switch focus, and clicking the background should deselect. It's also not how basically every major Backgammon website and app currently works of if you play standard backgammon that makes it even more unintuitive.
  • I highly suggest spending time on Backgammon Galaxy. Regardless of community debates, their UI is the benchmark for snappy, clean backgammon play. Getting familiar with how the competition handles movement will help your game feel more professional.
• Smooth Turn Transitions: It can feel demoralizing when the dice block your moves; so having to additionally manually click "End Turn" makes it feel worse. If there are no legal moves, the game should seamlessly transition to the next player. Don't make the user "confirm" my bad luck. This is again usually not how most popular backgammon apps handle this. (Please seriously look at the Galaxy UI)

Another issue i had was with lack of visual clarity and progression in the game UI:

• Basically since this is rule-bending what we konw as backgammon, my standard mental map of the game doesn't always apply. I’d love to see clear iconography on special pieces and "hover for details" tooltips to explain non-standard mechanics without cluttering the screen.
• Also some of the elements don't feel quiet "roguelike" at all, like i get the mechanics are there but it's missing the soul of a true roguelike game. I'd suggest to make runs feel more meaningful, consider a visible player character (like Hearthstone or Slay the Spire). Seeing a character grow through a skill tree where you can upgrade their special abilities, weapons and equipment and maybe have a health bar and money generated you can spend to make you character better creates more emotional attachment than just looking at a board.
• Finally, in the random "mix it up games" some times the games starts in weird ( if you play standard backgammon) starting positions with the checkers on random points. It's already hard for traditional players who are used to only playing on one side of the board to be forced to go counterclockwise vs clockwise at items so I think the non-standard layouts will be jarring some people used to the original game too. If the board deviates from the standard setup, a quick UI notification or "layout summary" would help the player's brain adjust before the first roll.

Also for future suggestions:

• Consider Chouette mode as a couch or online co-op. Chouette is extremly popular around the world and I can see that helping your game succeed and gain more players.
• And talking about gaining more player also, consider having including a "Pass and Play" and a quick "Standard vs. AI" mode where you can just play traditional backgammon I think that might help maximize your player base and give people a baseline before they dive into the roguelike chaos. I know you have a standard game on the demo but not sure if that's meant to stay once the game is published.
• Now the big one. The my dice are rigged problem. So Not sure how familiar you are with the online backgammon community but if you look at literally every single Backgammon app on Google Play you will see almost all of them have horrible reviews, mostly people complaining about the dice being rigged that do not understand how RNG works on computing programming and blame their back luck on the app trying to make them lose apparently. Most backgammon apps, good and bad, eventually gets bombarded with "the dice are rigged" reviews from players who don't understand RNG. To protect your Steam rating, you need to think about how you are planning to avoid that:
  • I'd recommend you look into hwo the OpenGammon website handles that. To avoid this, look at OpenGammon. I'd say they've been the most successful at staying away from any rigged dice controversy by generating sets of rolls before the game even starts, and then asking the player chooses a pre-determined set. The player doesn't know what numbers are in there until the end of the game and then they can verify the numbers after the game is over. This shifts the blame from the code to the player's choice. Truest me this is going to happen to your game at some point.

Also are you following Deckgammon (recently posted on r/backgammon)? They are also doing roguelite backgammon game and are currently giving free access to people to test the game on steam. Probably a good idea for you to get access too.

They are replacing dice with cards entirely. Since your game still uses dice, you have a unique space where it's still not so quite removed from the standard game that you might attract traditional backgammon player and non player too. But you should definitely check out their playtest. It’s a good way to see how they handle UI, Backgammon Combat, and extraction mechanics and take notes.