In my experience, there are two schools of thought when it comes to an element of random chance in strategy games:
1) It’s good.
2) It’s bad.
I’ve seen a lot of people run with #2 so far that they proclaim that a game that involves random chance is no longer about strategy at all, but just about luck. To some extent, they do have a point: I’m sure all of us have had that game where we played a perfect strategy that was a sure thing, only to pit our unlucky roll against our opponent’s lucky roll and lose everything to that one stroke of misfortune.
By and large, though, this is the exception, not the rule, and in the long run such possibilities keep a game more interesting — no matter how well you plan, no matter how well you predict and react to your opponent’s moves, sometimes you lose anyway.
It’s certainly frustrating to lose a perfectly-played game to a bad roll of the dice — but does that make it a bad game, or remove the “strategy” part of the game’s genre? No!
Well, not necessarily…
I can certainly see the appeal in knowing exactly how any given encounter will turn out. Take chess, for example: you know exactly what will happen if a pawn attacks a knight, or a bishop a rook. Now consider Risk: if you attack North Africa from Brazil with 5 pieces against your opponent’s 3, what’s going to happen? Well, you won’t know until you roll the dice…
(Now, I’m not saying that Risk is a great game from a strategy standpoint — I do love it, to the point that I own a dozen copies of it and its variants (Risk, Castle Risk, Risk Onyx Edition, Risk 2210 A.D., Risk Godstorm, Transformers Risk, LOTR Risk, Star Wars: Clone Wars Risk… I could go on) — but from a strategy standpoint it is rather shallow, especially compared to similar games that add an economic aspect and/or different unit types, like Dust or Axis & Allies. It is, however, an easily relatable strategy game, that pretty much everyone knows, which uses chance.)
To some, not being able to know the outcome of a given action means that the game is one of chance, not strategy; I strongly disagree, however, as a good or a bad strategy can make all the difference, even pulling victory out of bad luck, or defeat out of good luck. Consider Risk: In the incredibly unlikely case that a person rolls nothing but 6s on a turn, that person might decide to take advantage of that incredible stroke of good luck to conquer as many territories as he can. Such an approach, however, is doomed to failure, as his opponents regroup and quickly snatch away numerous territories because he spread himself way too thin.
Luck plays a part, certainly, but it’s useless without a sound strategy behind it.
I’ve also heard it argued that chance destroys the realism of a game. Putting aside what “realism” there is in the very premise of these games, I still argue in favor of chance. While it’s true that a Panzer tank will not likely find defeat at the hands of a cave man wielding a bone club, it’s just as true that not all club-wielding cave men are created equal: some are stronger, others are sturdy, some are just plain quick. But even that’s not the end of it: a cave man who is stronger than another cave man, and who would normally kick his ass without breaking a sweat, might find himself temporarily blinded by the glare of the sun off an unexpected puddle of water, or lose his footing on a loose stone he didn’t notice before.
Chance mechanics are an abstract means of coalescing all of these factors — and so very, very many more — into a simple mechanic that we can understand, and can incorporate into our strategies.
Sure, sometimes the results don’t always make sense — I can’t tell you how many Panzer tanks I’ve lost to Bronze Age spearmen in Civilization games — but to me these mechanics always make the game far more engrossing.
From a game design perspective, consider a game which uses a deterministic combat mechanic such that any given confrontation will always have exactly the same outcome, versus one which uses a chance-based combat mechanic. Let’s further consider that both of these games utilize units with varying strengths and weaknesses, an economy to purchase them, and a complex “battle form” system that allows for endless variation of battle formations even if you use the exact same units.
In fact, let’s run with that. Let’s assume two players are each given identical units, and are told to come up with a battle form to be pitted against one another. There’s a surprising amount of strategy in where to position units. If one of these two players’ strategy is slightly weaker than the other’s, though, this face-off under the deterministic game’s rules will always result in the stronger player’s victory.
In the chance-based game, however, a slightly weaker player still stands a chance against one with a stronger strategy — which results in both players being tested as battles go one way, then the other. In general the stronger player will win more often, but the weaker player isn’t completely shut out of the game.
This makes for a game that is more approachable by new players, as facing off against stronger, more experienced players is much less daunting.