Neat! The gameplay was simple but yet fun and relaxing. It could be a great mobile game.
As for feedback:
Something that confused me at first was the ?-Block. I thought it acted like a joker and also added to the score but could be placed anywhere as well, however it doesn't actually add to the score and only served to make the chain itself longer. Also maybe an "X" would be better than a "?" but a counterargument could be that it doesn't add to the score so an "X" would be a bit deceiving.
At first I tried to build up branching scores thinking that I'd scored gold only to be left with a mess.
I would have loved to be able to change the positions of my placed numbers and then confirm it (There can be an option to auto-confirm as an alternative).
The highlight effect was a bit too subtle in my opinion, it was hard to see what was going to be scored.
The game over wasn't very clear; I accidentally pressed the restart button thinking I could switch up the placement of the tiles I placed this round, since the current placement wouldn't work out.
Please don't take it the wrong way! At the end of the day, it's up to you what you do with the feedback, most of it are just minor QOL improvements. The game is fun and polished and the sound design as well as the visuals fit the game wonderfully. I simply believe you can even build upon it farther to make the game even more fun and addictive.