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MixingYourMetagamingMetaphors


Written 27 July 1996 by George F. Rice

This unpublished article formed the basis for deriving Elven Fire from The Fantasy Trip

One of my children’s favorite crafts is to half-fill an empty 2-liter soft drink bottle with water, add blue food coloring, and fill to the brim with cooking oil. The oil and water do not mix, of course, and by rocking the bottle they see a reasonable facsimile of ocean waves at the beach.

One of their favorite games, on the other hand, is The Fantasy Trip (abbreviated TFT). They inherit their bias from me, for I have found TFT rules to be highly logical, easy to apply, balanced, and more fun to play than competing systems. My store of programmed solitaire adventures, which can be played with the unmodified rules, makes the TFT gaming system even more popular in my household.

Convincing seasoned gaming friends to play used to be a problem, however, due to a quirk in the TFT rules: All die rolls use standard 6-sided die. Their impressive collection of 4, 8, 12, and 20-sided die simply weren’t needed for the worlds I created, resulting in a marked lessening of enthusiasm.

But are polyhedral dice and TFT rules like oil and water, destined to forever live separate virtual lives?

In a word, no. This article attempts to establish a rationale for using polyhedral dice within the TFT rules. In defining these rules, my goals were:

  • Polyhedral dice must be optional. Those using the original rules should be able to coexist easily with the new rules.
  • The balance of the game must not be affected. No inherent advantage or disadvantage should accrue the player who uses polyhedral dice.
  • The new rules must add to the game, providing the player with more options, more variety, and more fun than before. Polyhedral dice must not only look cool — they must improve the game as well.

Making a Game Plan

To avoid affecting the balance of the game, the player using polyhedral dice must make the same average roll as the player using traditional dice. A player who rolls a die many times will, on average, roll the sum of the largest and smallest possible value divided by two. So, the average roll on a 6-sided die is (6+1)/2 = 3½; for a twenty-sided die, the average roll is (20+1)/2 = 10½.

The average roll for multiple die is the sum of the averages of each individual die. So, the average damage for a broadsword, 2 6-sided die (abbreviated 2d6), is 3½ + 3½ = 7.

If we rolled 2 8-sided die for broadsword damage, we would have 4½ + 4½ = 9 — too much by two. But if we subtract 2 from each damage roll, the average roll will be (4½ + 4½) - 2 = 7. In terms of game balance, then, it doesn’t matter if you roll 2 6-sided die for broadsword damage, or 2 8-sided die and subtract 2. You will average 7 points of damage per hit in the long run.

Yet the effect is not precisely the same. The maximum damage using 2d8-2 is 8 + 8 - 2 = 14. Using 2d6 the maximum damage is only 6 + 6 = 12. Similarly, minimum damage using 2d6 is 2, but with 2d8-2 is 0.

This, then, is the improvement afforded by polyhedral dice. Individual broadswords may do 2d6 of damage, or 2d8-2, or even 2d4+2. Each weapon affords the same average potential for inflicting damage. But one weapon is more consistent (2d4+2), causing from 4 to 10 points damage per hit, while another varies much more widely (2d8-2), causing from 0 to 14 points damage per hit. Weapons take on more character, and battles become more interesting.

Defining the Boundaries

The new-and-improved TFT rules, then, are as follows.

  • Each striking weapon (sword, ax, mace, etc.) includes an intrinsic damage profile, obvious upon inspection, consisting of the number and type of dice to be rolled for damage, plus adjustment. For example, a broadsword’s damage profiles are 2d4+2, 2d6, and 2d8-2.
  • For missile or thrown weapons, the damage profile is associated with whatever does the damage. For a heavy crossbow, for example, the player may choose bolts which do 3d6, 3d8-3, 5d4-2, 1d10+5, 1d12+4, or even 1d20.
  • When purchasing weapons in a weapon shop, not all damage profiles may be available for a type of weapon. Players must choose from the available selection, as usual.
  • A character with the Armourer talent can modify the damage profile of a weapon, provided he has the tools necessary to make a new weapon of that type. The usual cost and required time for the modification is 10% of the cost and time required for a new weapon. Master Armourer is required for silver and exotic weapons; magic weapons cannot be modified.

Appendix A presents a table of weapon profiles. To determine the available profiles for a given weapon, find the TFT-defined damage on the table. All other profiles in its group are possible, and may be available at your local weapons shop.

Avoiding the Pitfalls

A damage profile like 1d4 -2, where the subtracted adjustment is larger than the number of die rolled, does not have the expected average value of (1+4)/2 -2 = ½. Since non-magical weapons cannot do negative damage (that is, increase the target’s strength), the actual average damage is (0 + 0 + 1 + 2)/4 = ¾, slightly higher! For simplicity, then, such damage profiles are not allowed in the new rules.

Launching the Attack

Not only does the range of possible values change with polyhedral dice, but also the statistical distribution (that is, your chances of rolling less than a given number). This change in distribution doesn’t matter when you are rolling damage, but it does matter if you are making an attack or saving roll.

The average roll for attack dice (3d6) is 10½, coincidentally the same as the 1d20 attack die popular with some other systems. However, your chances of rolling an 8 or less with 3d6 is about 26%, while your chances with a 1d20 is exactly 40% — a much better chance. If we plot statistical distribution for the two attack systems, we see that rolls below 10 are easier with a 1d20, while rolls above 10 are more difficult (the 1d20 distribution is the straight line).

While we could map each adjusted dexterity 3d6 to an equivalent 1d20 roll (for example, to hit with AdjDx = 8, you must roll 5 or less on 1d20), this solution is messy and unpalatable. If we are to consult a table for each attack, we may as well use one of those other gaming systems!

A simpler solution is to decree that either all players use 3d6, or all players use 1d20. If 1d20 is chosen, then the following rules should replace the “5 is automatic hit, 4 is double damage, 3 is triple damage” provisions of TFT.

  • A roll of 1 is an automatic hit. Roll a 1d10. A roll of 1 is triple damage, a roll of 2, 3, or 4 is double damage, any other is normal
  • A roll of 20 is an automatic miss. Roll a 1d10. A roll of 7, 8, or 9 means a dropped weapon. A roll of 10 means a broken weapon. Any other roll is a clean miss.

These two rules replicate almost exactly the results of the existing TFT “extreme roll” rules. If you like the critical hit rules of TFT, try this table with a second 1d20 each time an attack roll result is 1 or 2.

9-20No crippling hit
7-8Target loses use of right leg
5-6Target loses use of left leg
3-4Target loses use of weapon arm
2Target loses use of shield arm
1Target is hit in head and falls unconscious (ST=1)

More interesting still would be a table for exceptional success (1) or exceptional failure (20), giving a different result for each value rolled on a second 1d20. These two tables are left as an exercise for the reader, since they will be more interesting if they take into account the surrounding milieu.

Note that using a 1d20 for an attack die will change the character of the game somewhat, since it will be easier to hit with low AdjDx but harder to hit with high AdjDx. Experience has shown that this is not a significant change, especially if your friends are stuck on the belief that a 20-sided die is an attack die by definition.

Saving rolls using more than 3 6-sided die should be performed using 6-sided die; they are not “attack rolls” after all. When planning traps, your labyrinths can take advantage of the new-found flexibility in defining detect and disarm rolls. For example, a particular trap may require 5d8 vs. IQ to detect and 3d12 to disarm. Not only does this give you more control of the chances of success for particularly smart or dexterous characters, it also allows flexibility in the advantage afforded the character with Detect and Remove Traps talents (rolling 2 fewer 12-sided dice makes the trap much easier for a knowledgeable thief than usual!).

Sweet Success

Mixing oil and water may seem a strange recipe for success, until you see the excitement as the waves roll into the bottle-capped shore. Mixing polyhedral dice into the Fantasy Trip system can likewise increase your enjoyment of the game by providing more variety, flexibility, and options to your little corner of Cidri. Appendix A: Weapon Profile Table

1d6-31d6-2 1d4-11d6-1 1d42d4-21d6 1d4+1 1d8-1
2d6-3 2d4-11d6+1 1d4+2 1d8 1d10-12d6-2 2d41d6+2 3d4-2 1d8+1 1d10 1d12-12d6-1 2d4+1
1d6+3 3d4-1 1d8+2 1d10+1 1d122d6 2d4+2 2d8-23d6-3 3d4 1d8+3 1d10+2 1d12+12d6+1 4d4-2 2d8-13d6-2 3d4+1 1d8+4 1d10+3 1d12+2
2d6+2 4d4-1 2d8 2d10-23d6-1 3d4+2 1d10+4 1d12+3 1d20-12d6+3 4d4 2d8+1 2d10-13d6 5d4-2 3d8-3 1d10+5 1d12+4 1d204d6-3 4d4+1 2d8+2 2d10 2d12-2
3d6+1 5d4-1 3d8-2 1d12+5 1d20+14d6-2 4d4+2 2d8+3 2d10+1 2d12-13d6+2 5d4 3d8-1 1d12+6 1d20+24d6-1 6d4-2 2d8+4 2d10+2 2d123d6+3 5d4+1 3d8 3d10-3 1d20+3
4d6 6d4-1 4d8-4 2d10+3 2d12+15d6-3 5d4+2 3d8+1 3d10-2 1d20+44d6+1 6d4 4d8-3 2d10+4 2d12+25d6-2 7d4-2 3d8+2 3d10-1 1d20+54d6+2 6d4+1 4d8-2 2d10+5 2d12+3
5d6-1 7d4-1 3d8+3 3d10 3d12-3 1d20+64d6+3 6d4+2 4d8-1 2d12+45d6 7d4 3d8+4 3d10+1 3d12-2 1d20+76d6-3 8d4-2 4d8 4d10-4 2d12+55d6+1 7d4+1 5d8-4 3d10+2 3d12-1 1d20+8
6d6-2 8d4-1 4d8+1 4d10-3 2d12+6 2d20-25d6+2 7d4+2 5d8-3 3d10+3 3d12 1d20+96d6-1 8d4 4d8+2 4d10-2 2d20-15d6+3 9d4-2 5d8-2 3d10+4 3d12+1 1d20+106d6 8d4+1 4d8+3 4d10-1 2d20
9d4-1 5d8-1 3d10+5 3d12+26d6+1 8d4+2 4d8+4 4d10 2d20+19d4 5d8 3d12+36d6+2 10d4-2 4d10+1 2d20+29d4+1 5d8+1 3d12+4
6d6+3 10d4-1 4d10+2 2d20+39d4+2 5d8+2 3d12+510d4 4d10+3 2d20+45d8+3 3d12+610d4+1 4d10+4 2d20+5
5d8+410d4+2 4d10+5 2d20+62d20+72d20+82d20+9
2d20+10

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