That first one is really intriguing. There must be some religious significance there, but can't begin to think what it might be.
Were Old Norse playing blitz??

Interesting, no doubt.
I suppose you already know about the 12th century chess pieces of Lewis Island:
https://en.wikipedia.org/wiki/Lewis_chessmen

Im aware tzimakos! Thanx for link
I surely don't know what it is and maybe it has to do with something religious. Just as simaginfan I can't think what it could be

Interesting, no doubt.
I suppose you already know about the 12th century chess pieces of Lewis Island:
tzimakos as you are interested, a recent article https://www.chess.com/news/view/ancient-chess-piece-lewis-chessmen-sothebys

"A little known fact about the vikings is that they really liked board games, and their favorite game was Hnefatafl.
Hnefatafl is a game of strategy, somewhat similar to chess, though it is not derivative. Hnefatafl predates chess, and was the game to play until chess ousted it during the middle ages.
Hnefatafl was the game of choice for the vikings, and much of its popularity was due to the vikings spreading it around to the places the travelled to. Unlike most other strategy games, Hnefatafl features two unequal teams, which different goals, an attacking team, and a defending team. The attacker's goal is to capture the king, while the defenders goal is to let the king escape. The attacker also gets twice as many pieces, yet it is the defender that really has the advantage.
Though the game was the most popular game in the world during it's time, the rules were never actually written down. We know some rules by marked game boards which have been discovered, some rules from viking poems and song, and some rules written by an observer that couldn't even speak the language. However, by piecing together bits and pieces from different places, we can be fairly certain how the game was played.
I had never played the game before, in fact, I built this board just so that I could play the game. It turns out that it's really a fun game. The rules are simple but the game play is interesting and requires good strategy. I also discovered that my brother is much better at it than I am, which is a little embarrassing."
https://www.instructables.com/id/Hnefatafl-Board-The-Viking-Board-Game/

Interesting addition. The first link seems to suggest the use of a chequered pattern is somewhat Faustian but with Satan losing the game to G_d, making the walls of the churches defenses against the devil.

History channel confirmed that Ivar the Boneless played a game of Hnefatafl against Alfred the Great in their youth.

Nice stuff Kamala!!😁👍
Thanks! I remembered that Bronstein heard from Olafsson, that chess was part of the Icelandic culture...from the time of the Vikings!

I don't know if you know about Daniel Willard Fiske, Morphy's friend and the impetus behind the 1st American Chess Congress. Among other things, Fiske was a linguist.
In 1879 Fiske visited Iceland for his first and only time. One of the places he visited was Grimsey, an island off the northern shores of Iceland within the Arctic Circle where the climate is particularly harsh and unforgiving. Fiske was in awe of the remarkable inhabitants of this island. Still a poor man, Fiske managed to send them marble chess sets and boards as well as much needed firewood. At his death, as a rich man, he bequeathed the island a great sum of money ($12,000 - the most ever given to Iceland up to that time). He is well remembered in Iceland where his birthday, November 11, is celebrated each year and where he is considered the Father of Modern Icelandic Chess . He edited the first Icelandic Chess Magazine in 1901 (published in Venice) and donated thousands of chess books to the Icelandic libraries. In 1905 Fiske's famous book, Chess in Iceland and in Icelandic Literature was published posthumously.
There is (or at least used to be) The Willard Fiske Center in the U.S. Embassy in Reykjavík
"Chess in Iceland and in Icelandic Literature"
The Fiske Icelandic Collection in the Cornell University Library
"Willard Fiske in Iceland" by Provost W. H. Carpenter

I've searched a little on Hnefatafl and found a really informative entry by Murray in his History of board-games other than chess [can be borrowed in archiveorg]
"Tafl (pronounced tabl) was the older, and hnefatafl the later name of a board-game which was already played by the Scandinavian peoples before A.D. 400. It was carried by the Norsemen to Iceland, Britain, and Ireland, and spread to Wales. It was the only board-game played by the Saxons. After the introduction of chess into England in the eleventh, and Scandinavia in the twelfth century, hnefatafl fell out of use except in remote and isolated districts: the last mentions of the game as still played are from Wales, 1587, and Lapland, 1732.", p. 56
an early found item he gives is the following:
The Ballinderry gaming board in National Museum of Ireland [9th-11th c.??] in here
But an interesting passage is also the following [p. 61]:
"An English or Irish manuscript (CCC., Oxford, 122, see J. Armitage Robinson, 69 ff.) contains a curious attempt to give a scriptural meaning to hnefatafl which is here named alea. The text begins: ‘Incipit alea euangelii quam Dubinsi, episcopus bennchorensis, detulit a rege anglorum, id est a domu Adalstani, regis anglorum, depicta a quodam francone ct a romano sapienti, id est Isrl.’ (Aethelstan reigned 925-40, and according to the Four Masters, Duibhinnsi, sage and bishop of the family of Beinchair, died in 953.)
The manuscript uses the board and the arrangement of the pieces as a scheme for setting out a harmony of the Gospels, and this board is identical in its dimensions with the Wimose board. The game is played between two sides, one of forty-eight men, and the other of twenty-four men and a hnefi. The men are placed on the points of the board, so that there is a central point which is occupied by the hnefi (in the allegory, primarius vir, to show the unity of the Trinity). His twenty-four defenders are scattered symmetrically in the middle of the board, and the forty-eight attackers are scattered symmetrically on the points nearer the edges. The positions of the men are used to set out the details of the harmony. There are some errors in the diagram of the manuscript, but these can easily be rectified, and give the arrangement as shown in Fig. 25. The allegory is very artificial—the board contains 18 x 18 cells because the total of the four Evangelists, four Gospels, and ten Canons is eighteen; there are seventy-two men because the number of items in the harmony is seventy-two—but this need not concern us here. The important thing is that we have a picture of hnefatafl as played in the tenth century, which is consistent with both older and later descriptions."
So in Britain of the mid 12th century alea don't seem so demonized...
Corpus Christi College MS 122, f.5v [1140–1199 AD]
While I was searching for material around chessboards on medieval churches' walls for a previous blog, I've tracked 2 websites on the topic [here & here] for Northern Europe. The vast majority of them were just checkered patterns, something that maybe exists just as a decorative theme. Can't know for sure but I had tracked checkered patterns of the middle ages and elsewhere regarding these people. Anyway...
However two cases are surely worthy to be mentioned.
Ejdrup Church
In Denmark said to be built during 12th c [with some additions of the 15th]
Hourglasses next to chessboards! ??
St. Paul's Church, Bornholm
Denmark of around 1250. Here clearly a board for chess and tables-backgammon [??].