Inspired by Hnefatafl
As well as the many variations of hnefatafl old and new, there are some games inspired by hnefatafl which are different enough to be thought of as original games. However, that inspiration brings them into our story of the history of hnefatafl, which could legitimately be regarded as one of their parent games.
Breakthru, by 3M
Designed by Alex Randolph and published by 3M in 1965, Breakthru features a flagship and twelve gold escorts against twenty silver enemy ships. It was released as part of 3M's Bookshelf game series, abstract games with high quality components.
The aim of the game is the same as hnefatafl: for the flagship to escape from the board, or for the enemies to capture him. Movement and capture use different rules, though: for example, a player may move any owned piece (other than the flag ship) twice if not capturing, and capture is by a single-step diagonal move onto the victim, as a pawn captures in chess.
Thud of the Discworld
Thud was first published in 2002. It is the design of Trevor Truran, a fan of Terry Pratchett's Discworld series of novels. It depicts the battle of Koom Valley, in which the trolls fight against the dwarfs. Since its publication it has been mentioned in a number of Discworld novels, and is the theme of one of them.
The similarity to hnefatafl is not very deep. The rules of Thud are more like those of chess, with the moves of chess kings and queens being used for the pieces. The king piece of hnefatafl has been turned into a passive "troll stone" which cannot itself be moved or captured, the object of the game for each side now being the same: to eliminate as many enemy pieces as possible. The trolls combine their lumbering move with a powerful method of capture to make the game even.
But having the Dwarfish name of "Hnaflbaflwhiflsnifltafl", and a board with a large force at the periphery surrounding a small force at the centre, it looks like a game partly inspired by hnefatafl. Other aspects of the game, such as a kind of "double game" which has become a convention of hnefatafl, are adapted for Thud.
Celtic Royal Chess
An alternative interpretation of brandub has been promoted in the 20th century, the rules having been formulated "from studying the Ballinderry Board". There appears to be no historical evidence for this variation. So it could be considered a modern game inspired by the old tales of brandub, now almost universally considered a hnefatafl game.
Brandubh: Celtic Royal Chess features an interesting start layout rather like hnefatafl, but aligned on the diagonals. The rules of movement and capture are different from hnefatafl games, and the object of the game is not to escape with the king but to capture the enemy pieces.
In the 1980s this hnefatafl derivative was published as an "LP game", the size of the packaged game being the same size and shape as a vinyl LP. A "mother submarine" tries to escape with the help of eight defending submarines. Sixteen destroyers lie in wait to capture the mother sub. The board is decorated with coastlines and islands, which constrict the grid in certain places.
Movement is by a single step along a marked line, including the occasional diagonals marked on the board. Capture is as in hnefatafl, but there are a few points on the board where submarines can photograph defensive installations, which force the attacker to remove one of the destroyers from the board.