The discussion of theme in boardgames is very common. Some like theme more than quality, some debate what games have strong theme, and almost everyone will use the phrase "pasted-on theme" at some point in their gaming life. Theme is placed on a fairly high pedestal. Games which lack theme or strong theme-mechanic relationships are called abstract or criticized.
What is theme? When most gamers use the word, they refer to a relationship between a game and some "real world" setting, situation, or event. Theme also extends into the speculative worlds of fantasy and science fiction. Let's examine what I feel are the three areas where theme drives a game, and why it is so important.
Regardless of the final result, a clear theme gives the designer direction. Rather than narrow the possibilities--as you might expect--it creates them. Let's start with a simple idea in a designer's mind: a river running through the desert. Now let's brainstorm on that theme:
Are there pyramids? Is there farming along the river? Does the river flood? Is there travel/trade across the desert? Does the river area create a natural struggle for control?
If instead we start with a blank slate and no thematic guidance, in what directions do we go?
I have a pyramid. I roll a die and move up the steps that many spaces. Then I draw 2 cards and follow the instructions. If I reach the top, I can put an extra blue cube on any red space.
Pretty dry? It fits together like a poorly edited movie--a collage of unrelated actions. The effects don't match the causes. The whole is much less than the sum of the parts.
So where do we end up? Well, if you're a good designer, the theme can carry you all the way to Euphates & Tigris, or Ra, or Amun-Re. The final game doesn't even have to be completely faithful to the original idea. That idea was simply the catalyst.
How many times have you seen people say things like, "I just can't resist a pirate game!" or, "I just like killin' stuff!"? Let's face it--themes sell games. World War II, Trains, American Civil War, Pirates, Exploration, Civilization, Politics, etc.
Theme can manifest itself in the name of the game, the box cover, the board, the pieces, and even the money. Games with heavily themed production, especially those with high quality parts, are much more likely to get a second look and above average impulse buys. It doesn't even matter if the game is terrible.
Is this a bad? Not really. We are suckers for brain- and eye-candy. Encouraging publishers to give us high quality, highly-themes games, is a good thing.
Theme is not black and white, nor is it objective. We each draw our own lines separating thematic from abstract. In games where theme drives our play, we often picture the events taking place and use intuition from our own experiences to help decide our course of action. Once a game is reduced to numbers, grids, shapes, and charts in our minds, then it has been rendered abstract.
In games with very high theme (most wargames, for example), you are literally forced to think in terms of theme. You have a map with terrain and various units. The effects of movement, line-of-sight, combat, morale, etc. are typically modelled as they exist in the real world. Any choices you make relate directly to "what you would do if you were really there".
For many games, there are players on both sides. In Puerto Rico, do you feel successful as you ship goods back to Spain, or are you simply filling a 2x4 grid with brown cylinders? In Carcassonne, are you building cities and roads, or are you merely connecting polygons and lines?
In games with "lots going on", theme increases the fun factor and helps us intuit our decisions. In games with very simple mechanics, abstraction is often a better choice. Even if the game is themed, it is likely to feel abstract. Either way, the varied use and presence of themes in our games provides a wonderful and personally unique richness of experience.