I'm pretty bad at chess.
It's weird, because I love games. Give me a little luck or some hidden information and I'm good to go, but the total transparency of chess is just at odds with how I think. I'm one of those terrible players who initiates lots of piece exchanges just to simplify the board, and it still doesn't help. I used to take a certain amount of perverse pride in this, especially because I excel at Knightmare Chess, but nowadays I just acknowledge it with a bit of a sad shrug, and file it behind "Drawing" and "Playing the Guitar" as things I might try to get better at someday.
But I still try to know chess. There is no other game out there I can think of that is so rich in metaphor and private language. Every game of chess feels like it holds the promise of a story or a war. And that richness is part of why we casually use it as a metaphor for almost anything complicated, indirect and adversarial. Usually, this is a pretty lazy metaphor, but if you drill into it, you can often find some useful insights. Specifically, Chess provides an excellent insight on how to run open-ended plots.
One important idea in chess is the threat, because it controls the cadence of play. When one piece is in a position to capture another piece, it is threatening that piece. In many ways this is more important than the capture itself because the threat can be used to (crudely) try to control the other player's moves. Suppose I have a cunning plan for my rook over there, but you move a piece and threaten my bishop. Rather than go forward with my cunning plan, I now need to react to your move. If you're very cunning, you've got another move that will force another reaction. Keep me on the defensive and you control the cadence of the game. Unless I can break this pattern, you've got me on the ropes.
This move and countermove offers an incredibly useful structure for RPGs and their conflicts, in part because what looks very simple on the surface but is actually made out of several smaller parts that can all be informative.
The initial threat is easy to model in any RPG. It might be an actual threat, but it can really be considered a stand in for any kind of clear tension. Something bad that will happen, but has not yet. This sort of tension is the basis of most action. Someone's going to kill the duchess. A storm is coming in. Raiders will strike in the night. The Prince's secret will be revealed.
Whatever form it takes, the important thing is that something bad will happen if no action is taken, and that something is undesirable. Compared to a passive threat (The Duchess has enemies. Raiders have a base outside of town.) these are vastly more useful for games because they already have momentum. They transition directly to action, and provide a clear purpose. Without that clarity, it is easy to get hung up on the rocks of distraction and research.
Having started with the metaphor of the threat, let's look to chess for how to handle this. When one piece threatens another in chess, there are several ways to respond: you can block, retreat, capture, threaten or cover.
You can block by putting another piece in the way of the threatening piece so it can no longer threaten the original. Unfortunately, the blocking piece is now threatened (and thus, a block may well be a sacrifice) and if the blocker is captured, the original piece is threatened again. Thankfully, there's a bit more to it - the blocker also changes the nature of the fight by changing where it happens. The new location may be more secure because it's covered or otherwise creates difficulties for the opposing piece. Of course, the whole thing may have been a gambit to move the blocking piece in the first place.
Retreating is more straightforward. If your piece is threatened, you move it so it's no longer threatened. Simple enough. But it leaves an opening where your piece used to be, and your piece needs to go *somewhere*, and a good adversary can limit your available options by threatening the empty available to you. A retreat is dangerous because it hands tempo (control of the back-and-forth cadence of the game) back to your opponent, unless you can hid some sort of other move in the retreat.
Capture may be the most viscerally satisfying option; capture the threatening piece with one of your own to remove the threat. The problem is its rarely that simple - unless you opponent simply overlooked that his own piece was threatened, then its almost certainly a trap. The only reason an opponent would knowingly threaten your piece with one that is itself threatened is to force you to capture his piece. This will presumably either puts your piece in a bad position, or removes it from a place where it was doing something useful to you. Unfortunately, if capturing is the only way you can stop a bad move, then you may need to willingly step into the trap.
Threatening counters the move by making a move somewhere else entirely, and initiating your own threat, so that you now threaten one of their pieces. If they capture your piece, you will capture theirs. This is a tricky game to play because your opponent will make his decision based on whether or not the final position of pieces is to his advantage or not. This is partly tied to the value of the pieces, but is not limited to that. It's also important to look at how the pieces will be positioned when things shake out. Your opponent might let you take a pawn to capture a knight, but if capturing that pawn puts your attacking piece in position to threaten other pieces? He might hesitate.
An even more subtle threatening response is one which does not necessarily threaten another piece, but rather is all about board position. If an opponent responds to a threat with an apparently nonsensical move, then think hard about what the board is going to look like after you make your capture. It's possible your opponent is clueless, but more likely he's taking advantage of the fact that he knows your next move (the capture) and is positioning pieces to be in a stronger position at the end of it. [EDIT: A suggestion in discussion may result in this being broken out from threaten as Flank or Maneuver]
Covering is the last option, and it's a dangerous game. It puts a piece in position so that if the capture is made, the capturing piece will then get captured in turn. This is a straight tradeup, and even more than a threat, it calls for an explicit cost-benefit analysis. This is often the easiest thing to arrange, but its also a sucker's bet, since it puts the decision in your opponent's hand, and if he says go, he knows your next move. This is the one response to a threat that can't be used to counter a Check, and that hopefully illustrates its weaknesses. However, it's not entirely useless. It is actually a strong counter against very strong pieces, because the cost of the exchange is almost never in the attackers favor. That is, this works well against queens because the cost of losing a queen is usually too high. But for a closer exchange, its tough. This invites quagmire, but for all that, you'll see it a lot because it is often on only apparent option.
Ok, so these are a bunch of chess abstractions, but what do they have to do with anything? To my mind, these map VERY easily to options that players should consider when faced with a threat in a game, and as a reverse, to ways for a GM to response to player actions in a game. If you can identify a threat (that is to say, the source of tension) then it's easy to ask "In this situation, what are my blocking options? Retreat? Capture? Counter-threat? Cover?" and as you look at it from each angle, it should suggest options.
This won't necessarily work for every game. In a dungeon, these options tend to be greatly curtailed, but in a more open game, one with more "pieces on the board" as it were, this can be powerfully effective. And, certainly, you can never expect things to map precisely to chess. While move and counter is certainly the most common cadence of play, every now and again it gets disrupted by events in play, but keeping the underlying structure in sight can also help things.
All of this also points to a very important point that Chess illustrates well: the power of tempo. When one side is forcing a response from the other (as with a threat) then that side is in a superior position, and this ends up mapping to a lot of ideas about proactive vs. reactive play. Since the GM is usually the initiator, classic gameplay tends to revolve around the GM making moves and the players making counters - that is to say the GM being proactive and the players being reactive - until the GM runs out of moves (so to speak) and the players win. This works ok, but you can also take a lesson from chess to realize that it is incredibly powerful to change the tempo. A strong countermove can force your opponent to become reactive, allowing you to become the proactive party. This hot seat can switch back and forth over the course of a game of chess, and there's no reason it should not be able to do the same over the course of an rpg session.
None of this thinking demands that you be good at chess (thank god for that), or that you even like chess. Chess is just a tool here to help frame the kinds of challenges and thinking that's going to come up in any kind of indirect, adversarial play, much like you will find in most RPGs.
1 - Of course, this cadence can change very quickly, especially if the reactive player has been careful about his reactions or if the proactive player is too focused on his own plan. More on that in a minute.
2 - This is one of those rare cases where this model is equally useful to players and GMs, since it's all about thinking about how to respond to things and try to claim the initiative.
3 - A lack of clarity has its place, but only when carefully planned for. If it just happens (as it often does) then its not a good thing.
4 - Or he was hoping you would overlook the threat. Either option may be reasonable for novice-level play, and in fact are good indicators for it, but stop being options as play gets more sophisticated. However, in situations with muddled information (like RPGs), that is a more reasonable situation. However, don't just assume it's a muddle unless there's some real fog of war sort of problems afoot, and even in those situations, a threat may be a good way to flush out the opposition. If the enemy does something you can counter by punching him in the face, and you have a history of face punching, assume that if he shows his face for a punching, there's more to it than it seems.
5 - This is something of a recurring theme, and one of the most important things to keep in mind when you apply this model to stories and games. The apparent threat is not necessarily the real threat. What is often important is what you're not doing when you're dealing with the threat. This is one of those things that looks incredibly cunning and manipulative at first glance (think Xanatos Gambit), but in reality is very simple problem solving. I want to get into the building, but it has guards. I will distract the guards, and go into the building. Easy peasy. Easy enough that it's not hard to nest two or three of these in a pinch.
6 - This also introduces some muddiness into the clarity of chess. The value of pieces is well documented, but board position is far harder to quantify. An exchange based purely on piece value is predictable. One based on piece plus board position is less clear.