For the uninitiated, RPGs tend to have players roll dice to determine the outcome of any event the player wants to resolve which would have an element of randomness to the outcome. For example, you would roll to see if you hit a monster with a fireball, and then roll again to determine how much damage the fireball does to the monster if it connects. But you might not roll if you're, say, hitting a door with an axe, since inanimate objects tend to be easier to hit.
There was something in the Dresden Files RPG books that I really liked, and I think makes for a great jumping off point. This is the advice they give GMs when considering whether to ask their players to roll: "1. Consider success. 2. Consider failure."
When you're asking someone to roll for something, there is the implication that they could fail at what they're trying to do. For the game to be fun, both success and failure need to be interesting. Combat seems to cover this automatically; if you succeed at a combat roll, you're that much closer to victory, and if you fail, that much closer to defeat. But skill and knowledge checks, well, there are definitely right and wrong ways to handle those. Here's some examples as to how that might work:
The Inevitable Victory
Let's say there is a locked door, and a character with a skill for picking locks wants to get through it. If they succeed, great, they get to find out what's on the other side, but what if they fail? Some GMs might just tell the player to try again, and keep that up until he gets it right. That's boring. Same thing if you let every other player with a lock picking skills to take a crack at it, as the odds are good that at least one person will roll high enough to make it happen.
Oh, and if they get through that door? There needs to be something worth seeing on the other side; if it's nothing of interest to the game, then you shouldn't have had them roll to get through the lock in the first place.
The Quick Recovery
Let's take another scenario: This time, you have the player in a treacherous situation, like avoiding a trap or accident of some kind. The player rolls to avoid the trap but fails. The consequence? Let's say a small penalty, or some minor damage. This is a fine consequence. But let's say that you then avoid any situation where the consequence would matter . . . what was the point? If the trap did damage to the character, but the character immediately gets to sleep it off, then there was no reason for asking him to roll to avoid the trap in the first place.
The Necessary Success
Quick story: I ran a game in which my players spent a lot of time fighting an evil lich who had raised an army of zombies. At the end, they met with the leaders of the combined mortal armies to push back against the lich; the idea being that they were going to ask the military leaders to lead the charge against the lich. So I had a player roll to see if they go for it. He failed . . . and I just let him have it, anyhow.
What was I going to do? The game had been building to this climactic final showdown, why would I just cut it off because of a single roll? That roll should never have been called for in the first place.
So, I think I can see a few principles for calling for rolls in an RPG:
- Success needs to be meaningful to the player's goal
- Failure needs to have consequences that are both felt and tested
- The game cannot hinge on a successful roll