I like d100 RPG’s for the realism, flexibility and ease of play, but I constantly hit a wall when reading and playing many, as their systems seem to be far too clunky or mathy*. These are the ones that also generally fuel the d100 detractors and solidify their belief that d100 games are less user friendly than mechanically simpler games like DnD.

The reality is, d100 games are no more difficult in concept than any others and indeed are far more logical than most, but often lose their natural ease in application. This contradiction frustrates me. Theoretically, d100 games should be the most intuitive and teachable of RPG’s, but in reality, they often trip over their own convoluted systems.

Mythras is one example.

The basic principles of a d100 game, including Mythras are;

Roll d100 under or equal to a skill or characteristic. Under or equal is a pass, over is a fail.

Where they vary is in two base mechanics within that process.

1) Measuring critical successes and failures takes many forms, often simply coming down to a 0-5 or 96-100 range, sometimes though using a % value more or less of the base skill, which adds a ton of un-intuitive math especially when NPC’s are introduced. I dislike both systems. One is overly simplistic and illogically fixed, the other is overly complicated and mathy.

2) test difficulty is also applied in several different ways. Mythras uses the half or double skill system, meaning that again you need to work out fractions and multiples as you go, others (Openquest etc) simply add or subtract a value from the skill level, which is not a totally rational approach, just easy to apply. The Mythras one is a real bug-bear for me, being simply the most cumbersome of those out there, even if it is a little more logical.

I propose (and usually implement) a simple set of fixes, which are an amalgam of several ideas from past and current games and some older ideas of my own. These can be applied to any d100 game, usually only needing difficulty levels re-worded.

Basic principles stay the same, but a hard limit of 99 is set for all characteristic and skill test levels (this can be worked around using the parent systems fixes for +100% skills, but is cleaner if capped).

Critical success and fumble chances.

Doubles are critical results, good or bad (1 in 10, usually similar to the original systems math, but requiring none). Doubles in the pass range are critical successes and doubles in the fail range as fumbles or worse.

This can also use a table for a scaled effects linked to the actual value, avoiding the common; criticals used consistently as an over the top effect. For example 00’s (or oooh’s) are a simple, embarrassing fumble, but not catastrophic. 11 to 33 fails would have catastrophic ramifications (especially under pressure), reserved for unskilled types meddling where they should not and monumentally screwing the pooch. Similarly a passing 11 is a basic “better” result, while a 99 pass is a very unlikely legendary success reserved for grand masters of a skill showing off their superiority and further adding to their legend.

This doubles system fixes several issues.

It does not need any pre or post math. The roll determines if, the skill level determines what. A game master may also rule that NPC’s are immune to the benefits of their own crit rolls, making things even easier.

Test Difficulty is also handled differently.

Instead of dividing skill values (fiddly) or adding/subtracting from rolls or skill values (creating illogical curves), the players simply apply the rolled values in a specific order depending on difficulty. The terms used below for difficulty are just descriptive for this example and can be re-worded as needed to suit the game they are applied to.

A Mundane task uses the base 2d10, with the player deciding the best order for the rolled values. This means that generally a 50/50 chance has about a 74% chance of succeeding, but also, the player may apply the higher or lower rolled value as they need to determine who wins a contested roll.

A Standard test uses 2d10 in a pre-determined order, much as any system now. This means 50/50 is just that.

A Challenging task always takes the worst combination, which generally means a 74% chance of failing a 50/50 test.

A Daunting task uses 3d with the worst combination of 2 taken.

An Imposing task uses 4d etc.

I have not done the math comparing this with the other systems, but it works well enough and feels right. We use blue and red dice, reds being bad (and 10’s in Standard tests), blue being good (and 1’s). The GM only needs to hand the player their dice and they know what they are up against. The GM also has the option of handing the player neutral dice and interpreting the roll based on what they know, that the players do not!

Experience.

Difficulty also has an effect on earned experience points.

Standard test have a chance of earning an experience point (+1% skill). If a critical success is rolled, the character may attempt to roll over their current skill to add +1 to that skill if successful. This is normal learning through success in a characters career.

Critical pass rolls (any) rolled during a Challenging or harder test are an automatic experience point for the skill. The GM may even add +2% for Improbable passes. Fumbles at this level also offer a chance of learning, but require a roll.

These tests can be applied immediately, or in character down time.

The above system does not break any d100 RPG and many have some form of these systems already. They do however make systems like Mythras more enjoyable and easier to grasp for most, which is never a bad thing. Very rarely a situation comes up where a test or effect does not mesh directly, referring to the original system mechanic, but this is easy to change on the fly as are most things in d100 games.

The only issue this system can cough up is a habit of point generated characters starting with double value skills, but that is fine really, as it simulates “turning points” in a characters development. This is where edgy failures start to turn into equally edgy successes. Also character development from then on is usually achieved in single increments anyway, so after a session or two, many skills with be 1-3% over their starting double.

This has been successfully applied to Warhammer 1 and 4e, Mythras/M-Space, the BGB and other Chaosium games and to games that share some of these ideas already like OQ, Bare Bones Fantasy or Wuxia.

My own d100 RPG in the works, uses a slightly modified version, using the Mundane model as the Standard test, with higher base skills, but generally lower maximums. This version has a greater chance of a 50% test passing and base skill levels are closer to that mark, but skills over 80% are rare.

*To be clear here, the maths is not advanced degree stuff, but enough to put many off. The actual math can be solved quickly with a table or a calculator, but the type of math is not player friendly. I have found people are much happier to add simple mods to a single roll than divide a larger value to find a target to roll under. The latter tends to be a double negative.