If you can take a piece, you have to. If your opponent can take you, they have to. The winner is the first player to lose all of their pieces. Take me is a game that can immediately shift the attitude of a beginner student. If they are struggling to play well and often loses pieces, they are usually delighted to discover a version of Chess in which losing pieces is a good thing!
The winner is the first to lose all their pieces. If a player can capture a piece, then they have to capture it. If multiple captures are possible, they may choose the best one. The King CAN be captured. In the event of a stalemate, the winner is the player with the fewest number of pieces.
Encourage the student to look for unsafe squares. Point out an empty square that is safe, and how it is significantly different from an empty square that is not safe. Notice how the opponent's pieces do not exist only on their own squares, but also have a presence along the squares where they have the ability to move. Imagine the way a computer highlights possible moves for each piece and the shapes those patterns make. The Queen makes a star, the Rook a cross, the Bishop an X, the Knight a circle of squares. By visualizing these move patterns, it makes it much easier to see safe/unsafe squares.