The control scheme doesn't allow for a mix of KB&M. In order of precedence (clicking anywhere on the board makes it stick to mouse only): mouse > gamepad > keyboard.
You select a number from the selection wheel (mouse click, or Q/E) then "set" or "note" a number in a tile. Noting will write a small number. Erase/overwrite a number by clicking on the tile again.
There are three "Play Styles". Standard (recommended) highlights the selected number and greys out numbers that have been used in all 3x3 squares, but doesn't handhold you like Beginner that stops you from setting wrong numbers. Analog means no QoL stuff like highlighting, not that you have to manually scribble in numbers by hand.
To turn down BGM volume, go to second page of Options > Sound. I'd turn off sfx entirely.
You select a number from the selection wheel (mouse click, or Q/E) then "set" or "note" a number in a tile. Noting will write a small number. Erase/overwrite a number by clicking on the tile again.
There are three "Play Styles". Standard (recommended) highlights the selected number and greys out numbers that have been used in all 3x3 squares, but doesn't handhold you like Beginner that stops you from setting wrong numbers. Analog means no QoL stuff like highlighting, not that you have to manually scribble in numbers by hand.
To turn down BGM volume, go to second page of Options > Sound. I'd turn off sfx entirely.