Friday, 18 January 2013

Single Roll Resolution

If you have been reading the rest of my posts on rules systems, you will notice I hold simple, smooth, effective rules in high regard. I want a game to flow through its conflicts and combat like water. Grind is the enemy, as is needless complexity.  So, this is the post where I talk about my games and their rules.

I have 2 published games, and I am writing a third. They are each in different genres, but they share a common rules system: Rapidfire. The Rapidfire system is so name because that is how results to rolls should come about: fast. The premise of the system is to sacrifice some accuracy in simulation in favour of speed of play. For the most part, it works. Every roll in Rapidfire looks like this:

1d6+Stat+Skill versus Difficulty

There are only three stats and they go from -2 to +2, and there is a short skill list where every skill is rated 0 to 6. The idea is to keep the numbers low enough that you can pretty much count them on your fingers. Nowhere in the system will you have to do additions or subtractions of more that 5 or 6, and it avoids multiplication and division whenever possible. That's it. One roll to decide success or failure with numbers low enough that they can be sussed out in just a few seconds.

The real magic of the system is how it handles combat. The concept from the start was single roll resolution. One roll decides if a character's attack is a success or failure, as well as determining how much damage is done, how much damage armour stops, and ultimately the overall effectiveness of the attack. The way we accomplish all of this is by generating some static numbers, and gleaning more info from the roll. First, a target's defence (the difficulty of the attack roll) is a set number. Much like in the D20 system, there is no defence or dodge roll. Next, armour is designed as straight damage reduction: a character with 2 points of armour negates 2 points of damage. Finally, damage done is based off the roll. However much an attack beats the defence number becomes the lead. That lead is added to a static number based on the weapon being used to determine the damage being done. Armour subtracts from the damage, leftovers get marked down as damage to a character's health.

That sounds kind of complicated. It's not. Here's how it plays:
Player: "I attack with my sword"
GM: "His defence is 6"
Player: (Rolls 1d6, get's a 5) "Rolled a 5, with my stat and skill that's 8 total"
GM: "You hit. Lead is 2"
Player: My greatsword does Lead+3, so that's 5 damage.
GM: "His light armour resists 2 of that, 3 gets through. He only has 3 health, so he is down and dying."

Ta Da.
One roll to resolve attack, armour and damage. The rules make big hits REALLY big, and you never get that problem where you have an awesome roll to hit, but roll shit damage (I hate that).

There are some drawbacks to this system. It lacks the "spread" of results that games with larger/more dice have. It is also a linear distribution (all results are equal probability) instead of a normal (middling results are most likely) distribution. The system mitigates these problems with a few other fiddly bits that allow for adjustments to the dice, but we have to pay the price for speed somewhere.

Still, I love being able to wow players by resolving a combat between two heavily armoured battle mecha in just a few minutes instead of a few hours. I sold a lot of books on that simple demo.

That's all for now. Next time I think I will shift gears and talk about something other than rules.

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