post, I began talking about how knowing or rather not knowing the rules of the game can cause you to lose. In that article, I gave some basic descriptions of gamers at varying levels of rules acquisition and how likely they might be to make a rules mistake.
But, how does rules knowledge affect winning and losing?
I think of it as being the cause of winning and losing in 3 different categories.
1) Outright lack of rules knowledge. This occurs when a player doesn't know a rule or set of rules that could have an impact on the game. For instance, if a player is told that Thunderwolf Cav counts as cavalry, but they don't know that this gives the model fleet and a 12" assault range, they could erroneously place an easy kill point too close to the model. Lack of rules knowledge can consist of not knowing core rules, codex specific rules (especially those of your opponents' codexes), or both. I am of the opinion that it is of the utmost importance to learn and really grasp the core game mechanics, especially those of the models you use in your army. From there, you need to know your codex specific rules. There is no excuse for a marine player to not know about ATSKNF or combat squadding. Past that, as much information as you get gain about other codexes is good, but not mandatory. A good opponent should be willing to divulge any relevant rules or details as they unfold, especially in friendly games. In competitive settings (like Indy GTs), the burden of knowing ALL rules is more squarely placed upon each player.
This is a simple to avoid mistake, but it can definitely cost a player a game. Not knowing core rules and the specific rules of the codex you play can be considered a cardinal sin. It is also the easiest to avoid. Simply read the rule book. To beginners I would say, read, read, read. Don't assume you know the rules. If something comes up in a game, look it up. That is why the BRB has a glossary.
2) Misinterpretting rules. This is super ambiguous territory. GW is infamous for writing rules that have complete different RAI and RAW meanings. This can cause quite a few arguments. It also means that rules can be misinterpretted. For instance, deffrollas and the new FAQ make things interesting. Misinterpretting rules can lead to allegations of cheating among other things as well. This is probably the leading cause of the phrase WAAC as well. A misinterpretted rule can cause all kinds of problems.
Misinterpretting rules can also lead you to have issues in competitive setting where you can't go back and fix mistakes. If you make a move based on an erroneous or malicious misinterpretation of a rule and you are in a competitive environment, you are stuck and in events like the NOVA Open, you will get eaten alive.
In friendly games there is more leniency, but players with more experience should dissuade newer players from utilizing misuses of the rules and should themselves not try to use these on others.
3) Poor understanding of how rules interact with each other. The final issue I see with rules that can cost you the game is not knowing how rules interact to build synergy or to cancel each other out. There is a single rule for every situation in 40K. In some instances multiple rules overlap. For instance, how does a unit that gets to reroll hits interact with a model that forces successful to-hit rolls to be rerolled? How do defensive grenades affect furious charge? Having a poor understanding of the interplay between rules can greatly affect a game.
The most important lesson about rules is to know them. Read the BRB. Read your codex. Read other codexes. Learn as much as you can. When you think you know them well enough, go back and read them again. With such a complicated rules structure, the average player needs to refresh their rules knowledge on a regular basis. The best way to familiarize yourself with the rules is to play games, though. I would recommend getting in plenty of games with your local gaming group before you step into competitive games. In the end, the best thing to do is be an understanding yet firm player. Know your rules and make sure you can politely and respectfully support your position to opponents.