Oh no, not another short blog article about elements of classic abstract games! What can I say, guys? I'm on a kick.
Zugzwang is a concept in chess theory that refers to a serious disadvantage created by your compulsion to move. That is, because you need to do something on your turn, even when you would really rather not, you may be forced to fatally compromise your position.
It's a function, like so many other things, of tempo and leverage. A player who has the tempo dictates the terms of the match; his opponent is stuck reacting to what the first player is doing, until and unless he turns the tables. The longer he's unable to pull off this seizure of tempo, the narrower the chances are that he's going to do so. Opportunities and good moves rapidly fall away, until he's out of workable options, until there are no good moves left, and only bad ones.
Zugzwang is a concept you see in all sorts of abstract games; it's not limited to chess. You see it in draughts, for example. Indeed, that game goes one step further with the requirement that you jump an enemy piece even when it's a bad idea, and one of the core strategies of draughts is that you create situations in which you force your opponent to make disadvantageous jumps so that you can make an advantageous one on your own turn. You see it in Cribbage: a cunning opponent will force you to make a play that allows them to score on their turn. It turns up in Backgammon: even the sturdiest of primes will have to crumble eventually.
One place it generally doesn't turn up, however, is in wargames. In the vast majority of games, movement is recommended, but remains optional; you can move any, all, or none of your units on your go. Combat might be another story; there were plenty of games dating back to the dawn of commercial board wargames in which combat was mandatory between adjacent units, with "soak-off" attacks recommended to facilitate stronger attacks elsewhere.
There are probably more hex-and-counter games now, however, where combat between adjacent units is voluntary. Some folks might be nodding their heads here, because isn't that more realistic? After all, in situations where you have a strong attacker-defender pattern, the defender isn't going to give up the doubling or trebling of his combat factors from the terrain to attack his aggressor at paltry one-to-three odds. But it should be noted that, in my experience, the games with mandatory combat (the good ones, anyway) tend to end each combat with one side either being Eliminated or retreating two hexes, so you're generally never going to have a situation where you start your turn next to an enemy stack due to no fault of your own. That is, in effect, mandatory combat games tend to make combat a voluntary thing anyway.
Because of this, zugzwang isn't a word that gets thrown around a lot in wargaming circles (which is a shame; it's a fun word to say!). In fact, the Wikipedia article on zugzwang says point-blank that it doesn't feature in "Tabletop war games or role playing games" because "on his turn a player can simply decide to 'wait' or 'do nothing'." But I'm not sure if it's that simple.
If we're being absolutely literal, then, yes, zugzwang isn't a part of most wargames, because you can indeed choose to do nothing. There are a handful of games where a kind of "metaphorical" zugzwang is featured. If you've ever been forced to attack Richmond in a strategic-level Civil War game to appease the politicians back home, or if Hitler or Stalin have forbidden you to retreat, you are in fact being compelled to make a move that could significantly weaken your position. Mandated military operations in Twilight Struggle are another good example of this kind of sporadically-enforced metaphorical zugzwang. Something that's criminally under-explored in wargames is the simple and horrific fact that the political will to continue fighting a war is sometimes dependent upon making stupid attacks to give the illusion of action. Likewise, it's what even great generals have to do to avoid getting sacked. This is something I'm playing with in one of my designs, so we'll see what comes of it.
And if we want to get really metaphorical about it, there is something at least very similar to zugzwang in those games where the onus is on one player to reverse the tempo. I'm going to lose the game if I don't turn the situation around. The longer I sit on my hands, the more impossible it's going to be. I need to do something now, attacking from a position of weakness if I ever want the chance to be strong. I need to take this huge risk, because if I don't, I'm well and truly finished. The only way to avoid zugzwang - in the sense of finding myself bereft of useful options - is to inflict a sort of zugzwang - in the etymologically literal sense of "a compulsion to move" - on myself.