In the Yu-Gi-Oh! TCG, decisions are a part of every play, turn, victory, and loss. The decisions you make in the game constantly change the outcome. I’m not saying that the cards you play and your deck’s design aren’t important, but you need a lot more than that to do well in a match.

It has been debated over the years whether this game is more mental or physical. I’m here to say that this game is mostly a game against yourself.

How can that be? Isn’t this game about beating your opponent? Of course it is. However, that’s only part of the game. How well you do during your matches primarily depends on how good your decisions are. This goes along with the popular belief that if you place a great deck in the hands of a not-so-skillful player, that player won’t win any more than he or she might with a mediocre deck. His or her decision-making skills in the game are not developed enough.

The Yu-Gi-Oh! TCG involves making decisions based on imperfect information. Your decisions will be inherently flawed in some way, because there’s always something you don’t know—set cards, your opponent’s hand, or at least his or her upcoming draws. It’s like investing in stocks. You won’t always have the right pick and you’ll never have all of the information.

When you learn how to play a deck, you may think you’re only learning how the cards interact with each other. That’s true . . . to an extent. But actually, your efforts are more directed toward learning which decisions produce the most desirable results given any set of conditions. That’s why the more you practice with a certain deck, the better you get with it and the better your win percentage. It’s because you’ve learned how to make the correct decisions in most situations. That’s also why I never recommend building a brand new deck the night before a tournament: you won’t have enough time to learn the intricate second-by-second decisions you have to make in order to succeed on any given turn. That skill is developed by practice. It happens faster for some, but in every case it requires practice, practice, and, well . . . more practice.

Sadly, I know many players who like to build their decks the night before. They may get lucky and score some wins, and they usually attribute it to their awesome deckbuilding skills. I think it has more to do with the decision-making abilities they already have with certain cards. Adding a few untested cards to ones they’ve played before requires much less time to adapt, because they are already familiar with the rest of the cards they’re playing. So when someone says that he or she did well with a deck built the night before a tournament, remind yourself that that player may have had a lot of practice with 90% of the cards in his or her deck, and thus was able to quickly learn how to associate current knowledge with new cards. You should also remind yourself that this player probably won’t do well in the long run. It’s rare to see that kind of behavior actually rewarded. (If it is, that player has actually done him- or herself a disservice, but that’s a discussion for another day.)

Decision Trees

The concept of decision trees comes from mathematics. Here’s a quick definition from www.wikipedia.org:

A decision tree is a support tool that uses a graph or model of decisions and their possible consequences, including chance event outcomes, resource costs, and utility. A decision tree is used to identify the strategy most likely to reach a goal.

Interesting definition isn’t it? It has two distinct parts. The first part:

A decision tree is a support tool that uses a graph or model of decisions and their possible consequences, including chance event outcomes, resource costs, and utility.

During a game of Yu-Gi-Oh! you are consciously drawing mini decision tree maps in your mind. You then consciously make a decision based on its various perceived outcomes. You are always analyzing possible consequences, outcomes, resource costs (how many cards you have to commit to the play, etc.), and the utility of your cards in that decision tree.

The second part:

A decision tree is used to identify the strategy most likely to reach a goal.

This is also true whether you want to clear the field, deplete your opponent’s cards in hand, reduce his or her life points to 0, etc. Each decision tree you create in your head is used to decide which goal is the most worthwhile to you in any given situation.

While you don’t have the time to physically draw this type of diagram during a game, you usually draw thousands of them mentally while you play. You may see yourself winning on that turn or clearing the field, or you may see yourself as you make the wrong decision and are trumped by your opponent. Either way, it is critical to understand this concept. So much of your success during the game depends on how well you make decisions.

The Nature of Imperfect Information

Perhaps the most frustrating (and exciting) part any card game is that the information you receive from your opponent or the situation is not always right on the money. It is truly a game of probabilities. You don’t have to be a mathematician to understand probabilities or decision trees. The simple concept of imperfect information is critical to your understanding of this game (or any other, for that matter). In the Yu-Gi-Oh! TCG, you are constantly faced with imperfect information. Nothing is ever a sure thing. You may be wrong at some point and that’s OK. You only need to be right a good amount of the time to get by.

It’s a lot like the saying that “20% of what you do accounts for 80% of what you get.” It’s called the 80/20 rule. In Yu-Gi-Oh! terms, you could say that “20% of your decisions account for 80% of your results.”

From this rule, you can also infer that you only have to be right some of the time. What matters is how big the reward is when you are right. Think about the average game of the Yu-Gi-Oh! TCG. Most of the time, it consists of expected decisions and obvious plays. Everybody has a general understanding of basic “good” plays. But have you ever come to a point in the game when you are faced with a difficult situation? Most of the time, it involves a decision tree that you’ve never come across before, or maybe a decision tree that you have had difficulty with in the past. Either way, it’s tricky and you have to act fast: you only have a few moments to decide.

What to do . . . what to do . . .

Often, this type of situation will largely determine the outcome of your game for a variety of reasons: your emotions afterward, the result of your decision, the next few turns, and so on. The lesson is that these “big” individual decisions may win you (or cost you) the game. My testing partners and I once made an effort to find out which decision at what time determined the fate of the game. Needless to say, we encountered some interesting results.

That topic, however, is for next week. Thanks for reading, and be sure to stop by then!