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Wednesday, November 21, 2012

Resolution Options: 3d6 or 4d6

I've been thinking a little about d6 alternatives to the standard d20 attack roll. Not that I plan on ditching the d20 in most cases, but I thought I'd consider the options.

The most obvious would be to try to keep as close to the d20 range and roll high methodology as possible. That would be a 3d6 roll (3 to 18 range.) What would you call this? Target 3:18?

The behavior of the dice would not be the same, though. You would have to live with the fact that the bell curve makes armor differences more pronounced, and not all probabilities would be close to the d20-based approaches. AC 9 would have higher odds of success, AC 7 is about where AC 9 is under the standard approach, AC 2 is very hard to hit.

Adding a die to make 4d6 would still involve a bell curve, but you could keep the target numbers in the official table or use Target 20 and not mangle things too much. AC 9 would still be more likely to succeed. AC 2 would not be as difficult, though. The downside? You would call it Target 4:20.


  1. I think the downside is the curve itself, which magnifies modifiers unpredictably. A +1 is worth more if your chance is high or low than in the middle.

    Then again Car Wars Deluxe does it on 2d6 with plenty of modifiers for equipment, skill, range, smoke, and paint on your windshield.

    I could see a game where all the saving throws and skill checks were based on stats, so if you want to build a fire you just roll Xd6 under Wis or something. If it's really dry out and kindling is plentiful, roll 2d6 (50% chance for 7 stat). If it's regularly damp and cool, not much kindling, 3d6 (50% chance for 10.5 stat). If it's cold, icy, wet 4d6 (50% chance for 14 stat). If you're on a howling glacier 5d6 (50% for 17.5 stat).

    1. I could see a game like that, too. It's The Fantasy Trip. But I was going to talk about roll under in a separate post. And a couple 2d6 methods, in their own post.

  2. You could also let the player choose how many d6 to roll, with a larger amount being a safer approach and a smaller amount more likely to succeed but riskier.

    That is, roll Xd6 under target number, but if all dice come up 1 you fumble.

    Assume TN 7.

    If you choose to roll 1d6, you're going to definitely succeed even if the target is difficult, but you have a 1 in 6 chance to fumble.

    2d6 gives you a 50-50 chance to succeed, but a 1 in 36 fumble chance - almost never.

    3d6 makes success difficult, but you're almost never going to fumble (1 in 216).

    Make fumbles really harsh like "you hit yourself instead of enemy, full damage" or "your spell went wild and now there's lightning bolts coming from your hair".