Single-step Hnefatafl Games
Occasionally you'll see hnefatafl games on 9x9-square boards, with rules that allow pieces to move only to adjacent squares. They also share the same starting layout, with the defenders arranged in a square instead of in a cross shape as in tablut.
These rules are quite common. So far I've seen them in the 1970s game Papillon's Escape, Jeff & Jennie Loader's book "Making Board, Peg & Dice Games", John Astrop's book "The Pocket Book of Board Games", and the hnefatafl game made by Jumping Frog toys.
The most common set of rules for these games are as follows:
1. The game is played by two people on a 9x9 board, with 25 pieces: a king and eight defenders on one side, and sixteen attackers on the other.
2. At the start of the game, the king sits in the centre, with his defenders forming a square around him; the attackers are in T-shaped formations around the edge of the board, as in the picture.
3. The king's side makes the first move.
4. In a turn one piece is moved to an adjacent square along a row or column (i.e. not diagonally). All pieces move in this way.
5. Attacking pieces may not sit on a corner square.
6. The king is captured by surrounding him with four pieces, one in an adjacent square on each side of him.
7. A piece is captured when the opponent moves to occupy two opposite sides of it along a row or column.
8. A piece may safely move between two enemies. If the enemy wishes to capture it, one of the enemy pieces must be moved away and back again to effect the capture.
9. The king wins the game by reaching one of the four corner squares.
10. The attackers win when they capture the king.
There are some variations on this. In Papillon's Escape, the king needs only to reach the edge of the board, and is captured in the same manner as other pieces.