d100 system. Roll High or Roll Low?

[Asmotherion]

If you were introduced to a d100 system, what would you prefear between Rolling High or Rolling Low? Rolling high, would mean the higher the result of your d100 roll, the better it is, while Rolling Low is the exact oposite.

This is a gallop for a d100 system I am currently developing, and would like to have some player feedback.

[LibraryOgre]

I prefer "highest successful roll". I find it easy and intuitive.

Let's say you have a 75% and I have a 50%. We both roll; the better roll wins.

If you roll a 60%, you will have succeeded, and I cannot possibly match that, since if I roll a 60%, it's a failure. But if I roll a 49% and you roll a 40%, I win... you're better, usually, but this time, I came out ahead.

I've seen others who prefer "whoever succeeds by the most", but that adds a layer of math that I don't find helpful. The alternate method is "roll d%, add skill". In the above situation, where I roll 49/50% and you roll 40/75%, you win because 40 (roll) + 75 (skill level) is greater than 49 (roll) + 50 (skill level). In that version, if neither of us had reached a total of 100, then we'd fail.

[Yakk]

I like d% systems that use the fact that d% are two dice. Here is a simple trick: read the two d10s in both directions.

Suppose you need a 50 or under and you roll a 19. This is *also* a 91. One of the two directions was under 50.

You can get 5 different levels of success quickly from a single roll:
Doubles and failed: fumble
Both directions fail: failure
One direction succeeds: partial success
Both directions succeed: success
Doubles and succeeded: critical success

Crit+Fumble sums to 10% of rolls always.

At 50% skill it is 25% success, 50% partial 25% failure.

Add your Success + your Partial or better chance and you get twice your skill. At low skill levels, most of this is in Partial -- at higher skill levels, Partial growth flattens out, and Success goes up faster.

The goal is to use most of the skill% range as being interesting. I find skill checks in % games tend to be "well, I have a 15% chance, this is a hail mary" or "I have a 85% chance, sort of a given".

With the "both directions" trick, low skills are hoping for a partial success, while high skills are hoping for a full success.

Mathematically, it is very similar to rolling twice for every check and counting how many successes you get in total, because reading d% in both directions is relatively uncorrelated.

...

Suppose you have a 42% skill. You make some checks


70 or 07 - partial
38 or 83 - partial
41 or 14 - full, both are <= 42
16 or 61 - partial
57 or 75 - failure

as expected for a middling skill%, most of the rolls are partial successes.

...

Anyhow, in such a system, it is easiest to be roll-under I think.

Also, I made 00 be zero, not 100. As 00 is the best roll (always a crit) and 0X is also good it is nicely monotonic.

[Amechra]

I prefer "highest successful roll". I find it easy and intuitive.

Blackjack rolls! I love them because they give you an easy, math-light way of calculating degrees of success.

@Yakk I've mostly seen "pick which die is the 1s place and which is the 10s place" as a form of advantage. For example, a roll that involves a Passion in Unknown Armies lets you "flip-flop" the roll, which can massive improve your chances. Using it as the central mechanic of a game seems kinda interesting, though.

[Yakk]

Blackjack rolls! I love them because they give you an easy, math-light way of calculating degrees of success.

@Yakk I've mostly seen "pick which die is the 1s place and which is the 10s place" as a form of advantage. For example, a roll that involves a Passion in Unknown Armies lets you "flip-flop" the roll, which can massive improve your chances. Using it as the central mechanic of a game seems kinda interesting, though.
You can retrofit it directly into many d% games. It isn't hard to invent partial and full success fiction.

[LibraryOgre]

The flip-flop could even work as a makeshift advantage/disadvantage system.... and a critical system, if "both ways the roll went would be successful" were your critical criteria.

[Yakk]

The flip-flop could even work as a makeshift advantage/disadvantage system.... and a critical system, if "both ways the roll went would be successful" were your critical criteria.

Criticals as doubles works: A 40% skill has 4% crit chance, a 90% has 9%. Also fumbles.

If you value a miss as 0, partial as 1, full as 2, fumble as -1 and crit as 3, expected value is 2.1S-.1 (.1S-.1 is the fumble/crit component and is approximate; Partial and Full is exactly 2S.)