Main motif of this puzzle: Back-rank mate
In back-rank mate, a rook or queen checkmates the king on the back-rank. The king cannot escape to the next rank, because it is blocked in by its own pieces.
Learn more in this guide.
The hint button is in beta test. We recommend to use the button only after you've thought about the puzzle for some time without finding any idea.
Read more about the hint button in this blog post.