From Wikipedia:
Tafl Games
Tafl games (pronounced [tavl]), also known as hnefatafl games, are a family of ancient Northern European strategy board games played on a checkered or latticed gameboard with two armies of uneven numbers. Names of different variants of tafl include hnefatafl, tablut, tawlbwrdd, brandubh, Ard Rí, and alea evangelii. Games in the tafl family were played in Norway, Sweden, Denmark, Iceland, Britain, Ireland, and Sápmi.
Tafl gaming was eventually supplanted by chess in the 12th century, but the tafl variant of the Sámi people, tablut, was in play until at least the 18th century. The rules for tablut were written down by the Swedish naturalist Linnaeus in 1732, and these were translated from Latin to English in 1811. All modern tafl games are based on the 1811 translation, which had many errors.
New rules were added to amend the issues resulting from these errors, leading to the creation of a modern family of tafl games. In addition, tablut is now also played in accordance with its original rules, which have been retranslated.
Hnefatafl
Hnefatafl (sometimes now referred to as Viking chess) was a popular game in medieval Scandinavia and was mentioned in several of the Norse sagas. Some of these saga references have contributed to controversy over the possible use of dice in playing hnefatafl.
The rules of the game were never explicitly recorded, and only playing pieces and fragmentary boards are extant, so it is not known for sure how the game was played. If dice were in fact used, nothing has been recorded about how they were employed. Archaeological and literary sources indicate hnefatafl may have been played on a 13×13 or an 11×11 board.
Hnefatafl became a popular game in Northern Europe during the Viking era (end of the 8th century to 1000 CE), a turbulent time full of conflicts. When chess became a popular game during the Middle Ages, the rules of hnefatafl were forgotten over time. Hnefatafl was particularly popular in Nordic countries and followed the Viking civilization to other parts of Europe, primarily to the British Isles and the Viking country of Garðaríki in what is now part of Russia.
The game developed differently at different locations. Archaeologists have found editions in places such as Ireland and Ukraine. Hnefatafl literally translates to “fist table”, from the Old Norse (equivalently in modern Icelandic) hnef, ‘fist’, and tafl, ‘table’.
Modern Hnefatafl
The rules for Norse tafl were lost, but in the 1900s attempts were made to reconstruct the game based on the rules for the Sámi tafl game tablut. The rules for tablut had been written down in the 1700s, and translated from Latin to English in the 1800s (see § Tablut). Unfortunately, the rules were poorly translated from Latin and gave unbalanced gameplay, mainly due to the mistaken idea that the king must be surrounded on four sides to be captured – instead of two.
Different innovations were made to create a game that favoured the defender side less, such as limiting the king’s escape possibilities to the corners (instead of the entire edge of the board), making the king “weaponless” (unable to participate in capture), making the initial starting points of the attackers inaccessible for the king, and making it easier to capture the king against the corner fields of the board.
Today, many different versions of modern hnefatafl are in play – both online and on physical boards that are sold commercially. One variant used in tournaments is Copenhagen hnefatafl, which also features a “shield wall” mechanism to capture several soldiers at once, and an “exit fort” rule that enables the king to escape on the edge while otherwise being limited to escape in the corners.