Thoughts on the King's Defensive Strength

Thursday, 19th September 2013

Many of us are used to rule-tweaking to try and achieve balance in new and old variants of hnefatafl. Many of the tweaks involve the powers of the king. Some limit the king's movement, others his power of capture, but the ones I've been thinking about today involve his defensive capability. That is, is he captured by being surrounded on two sides or on four?

It's obvious that a king who is captured like other pieces will be weaker than a king who needs to be entirely surrounded. It will be easier for the attackers to capture him; it's actually very difficult to achieve a four-sided capture.

But there's a slightly more subtle shift caused by having a king captured on two sides. While it appears he's the equal of all other pieces on the board, in fact he's a lot more vulnerable. Every time he's threatened, he or one of his guards must address the threat or lose the game. This is unlike the other pieces, where a threat may be ignored, or may be delayed by making a counter-threat somewhere else on the board.

There is no counter-threat that the defenders could make that would deflect the attackers from capturing the king. Only those counter-threats that are at the same time blocking or fleeing moves would stop the attackers, and they don't count because, basically, they're blocking or fleeing moves.

So not only is this egalitarian king weaker than his enemies; he can weaken his whole side who will lose the initiative whenever the king is threatened. In this he could seem weaker than a weaponless king who is captured only when surrounded on four sides. In this case particularly, the defenders have to escort their king to the edge or corner.

There is the variation in which the king is captured as other pieces, unless he's on or beside the central square, in which case he needs to be surrounded by three or four pieces. This is becoming the accepted rule for the historic tablut game, and it's a more significant variation than it might appear at first. The king can be left relatively safely at the castle, and only when he sets out does he need his bodyguard. So the strategy of this game may be markedly different, the king's pieces being able to scout and skirmish more boldly at the beginning of the game.

This is food for thought when tweaking rules. If you want to play with the idea, click on the "Play" link, select the rules for tawlbwrdd or brandub, and maybe increase the size of the board too, to see how the dynamic changes with more pieces and more space to manoeuvre.