There was a thread on the Redbrick LLC forums a few weeks back talking about “cooperative actions” and how they should be handled in Earthdawn — using an airship captain as one of the examples. Rather than have each individual sailor roll, the poster wanted to know how to apply the crew as a bonus to the captain’s roll. Earthdawn doesn’t really have any kind of default method of handling things like this — something the original poster felt was a shortcoming.

As I was exploring the idea and how I would handle it, I kept coming back to the question of why you need to come up with a general rule for a situation that varies depending on the circumstances. Personally, the way I would handle it would depend on what was going on at the time, and what the roll is trying to accomplish.

Which brings me to a more fundamental question. When do you roll?

If you’ve spent any time in the role-playing game community, you will probably have come across a couple of different schools of thought on this question. Personally, I think that rolling should generally be reserved for times when the outcome of a particular action is in doubt and the results have potential that affect or be affected by the player characters.

This second part, I think, is the most important. The player characters are the most important characters in the game, and the only part of the game world the gamemaster does not have control of. One of the main purposes of an RPG rules system is to define (and limit) the interactions of the shared play-space. The amount of influence the rules have can (and frequently does) vary from group to group, session to session, and even within the session — combat, for example, generally has a much larger rules influence than any other  part of the game.

When the outcome is not in doubt, there is no need for a roll. When the outcome has no effect on the PCs, or cannot be affected by the PCs, there is no need for a roll. These are pretty straightforward, and I don’t think anybody would argue with them. Combat typically has a large degree of uncertainty, and the outcome can have a significant — potentially fatal — effect on the player characters, so rolls make a lot of sense.

It’s the edge cases that are interesting, and where you are likely to find the most range of opinions (exactly where the edge falls is another point of debate). Let’s take a look at an example from an old Earthdawn adventure — Terror in the Skies. At one point during the adventure, the player characters are riding an airship to Talon Kaer, and there are strong winds and nasty weather to contend with.

When do you roll?

Do you make rolls for the large airship approach? The smaller airboat heading toward the cave entrance? Setting aside what the adventure itself presents, the decisions of when to roll say a lot about the individual play style of the person (and group) making the call.

I don’t have a solid answer — and that’s the whole point. But it is a question that any GM worth the title needs to keep in mind when planning their game — and during the game itself.