I noticed you took some effort in the game's presentation with that 3D animation. It really got the vibes of some underground oldschool PS1 games, and there's a number of Itch.io users that enjoy this kind of style. I felt nostalgic watching it and I thank you for this.

Now, for the game itself, if you plan to keep developing it, I think you should start to study and apply some User Experience Design (UX Design) in your interface, because you already have a user profile system, a checkpoint system, a completion Indicator, a timer, a rating system, and maybe in my playthrough I even missed some more functionalities. You nailed this part, now this game needs to be more pleasing and addictive to interact with it by recieving some UX love in it (because Sudoku is already addictive enough! I tend to pass many hours solving these if I don't set up an alarm to stop playing it!).

I also experienced this bug. Don't know what I did to cause this.

___________________________________________

############################################################################################
FATAL ERROR in
action number 1
of Alarm Event for alarm 0
for object controller_info:

Push :: Execution Error - Variable Get -5.custom_page(100118, -1)
 at gml_Object_controller_info_Alarm_0 (line -1) - <unknown source line>
############################################################################################

Interesting game haha I enjoyed playing. I used to play a lot of Sudoku but I tend to forget how to play these types of games (like chess) as time goes. It was a memory blast remembering how to play though. Great job!