I would rather summarize the rules precisely. Mainly, the game board for 2 or more players can be generated completely randomly, because the primary goal is to see who will be the first to have no legal move. Whereas solo mode is like a classic puzzle, it must always be solvable. And that's probably not possible with some combinations. I asked the AI and it gave me this example:
R 3 3
2 2 4
4 1 B