This is the fifth in my ongoing series of columns devoted to the art of gamemastering. In my first column, I laid out the four roles of the gamemaster (judge, world-builder, adversary, storyteller), with judge as the most important role. In my second column, I explained the agency theory of fun, and showed how by focusing on objective rules, honest dice, and player choice, you maximize the fun for your players in the long term. In the third column, I discussed how a gamemaster should weave a story based on what has happened in the campaign, rather than what he wants to happen, and offered a technique for building story webs for emergent narrative. In the fourth column, I introduced the gamemaster as Adversary, and cautioned against adversaries with god-like powers. Now we'll turn to the question of who your adversaries should be, and how they should behave.
Adversaries Are Made of People!
It seems an obvious point, but the best adversaries are people (loosely defined as "sapient creatures"). People generally find the challenges posed by other people to be the most interesting; witness the rise in the popularity of online gaming.
Of course it's true that not every adversary needs to be a person. Dungeon traps are classic adversaries: They pose challenges that test the players' determination and cunning. Sometimes the environment itself is adversarial. Natural disasters, wilderness obstacles, and catastrophic weather can all pose challenges to the players, but a campaign where the main villain is, for instance, an earthquake is likely to be an uninteresting campaign. Add an Elder Elemental Cult actively promoting the earthquake and fighting against the would-be heroes, and it gets more interesting again.
Still, even when the adversary is a person, it needn't be an enemy. An adversary just needs to be a character who poses challenges. The adversary could be a foil, who serves to bring the protagonists into sharper focus. The adversary could be an ally who causes more trouble than their worth, like Lois Lane for Superman. Or it could be a rival from the same side who makes the heroes stay on top of their game. The latter is an under-utilized, but highly effective adversary.
In my Classic D&D campaign, I created a rival adventuring party, "Imperial Vanguard," that wandered the map and cleared dungeons in regions near the PC adventurers. I introduced the Imperial Vanguard by having the players find their next dungeon already cleared of monsters, with a bold flag planted bearing the I.V. standard outside the entrance. Because the two parties weren't enemies per se - indeed, I.V. was technically an ally to the cause - the players could not simply confront and destroy them. That made I.V. even more challenging as adversaries. Without any possibility for direct confrontation, Imperial Vanguard suddenly became a factor in the party's every decision: Where should we explore to make sure we get there first? How long can we afford to rest without Imperial Vanguard cleaning the dungeon out before us? And so on. For a long time, the monsters in our campaign were just the means to the players' end of beating Imperial Vanguard.