I added a new version, simplified the menu, added a solo mode for the 4x4 board, both 3x3 and 4x4 modes generate a solvable game board from several assembled sets of cards. After selecting the game mode, a colored marker appears, indicating the difficulty of the generated game board.
// 3x3
'1,1,1,2,2,2,3,B,R': '🟢',
'1,1,2,2,3,3,4,B,R': '🟡',
'1,2,3,3,3,3,4,B,R': '🟠',
'1,2,3,3,4,4,4,B,R': '🔴',
'2,2,3,3,4,4,4,B,R': '🟣',
'2,3,3,3,4,4,4,B,R': '🟣',
// 4x4
'1,1,1,1,2,2,2,2,3,3,3,3,4,4,B,R': '🟢',
'1,1,1,2,2,2,3,3,3,3,4,4,4,4,B,R': '🟡',
'1,1,2,2,2,2,3,3,3,3,4,4,4,4,B,R': '🟠',
'1,1,2,2,2,3,3,3,3,3,4,4,4,4,B,R': '🔴',
'1,2,2,2,3,3,3,3,3,4,4,4,4,4,B,R': '🟣'