Everquest's Internal dice mechanic - anyone know?

[TheRusty]

After reading up on some stuff, it appears to be...

• Ability Scores don't actually have any effect on determining the outcome of an action (a tradeskill click, an attack, etc) Instead they affect some base mechanics (damage range, base AC / HP / MANA, skillup chance)

• Skills Are where everything "actionable" is. Basically the game sets a "difficulty" based on the gap between your skill rating, and the target number (A tradeskill item's skill level, an enemy's armor class or spell resist, etc) and then "Rolls Dice" against that difficulty. The higher you get against the difficulty in combat, the better your outcome (Closer to damage cap for spells and attacks, or crits for Warriors / Wizards).

• There is an "critical failure" system in there as well, where if your roll is low enough, you fizzle your spell, miss a swing, or fail a tradeskill combine even on a trivial opponent or item. This seems to have various modifiers and limitations; School Specialization reduces fizzle chance, and if your skill rating outclasses the Difficulty Number enough, you'll just always succeed (it seems to be that if the difference is 200 or more). There does not appear to be a "critical success" chance, beyond obviously criticals on warrior attacks and wizard spells. Essentially, for most "actions" you have a maximum of 99% success chance, unless you supremely outclass the target number.

In terms of actual "dice," who the heck knows, I would guess that EQ uses a 0 - 999 roll, basically a percentile check x10, given the likely preference for a "round" number, and the fact that the possible gap between skill and target number is at least 255. it may be a smaller range, but I don't think exact numbers matter, we can shrug and say "basically Percentile"

For playing the MMO, basically this means that +Skill items are absolute gold, with +Base Stats items (Mana, HP, etc) being next-best, and +Ability items being least important. Basically you want to max ability scores just to maximize your innate base stats, then you want to add more base stats on top of that, and you will always want +Skill items if you can get them (I may be wrong, I don't think there's any in P99? I'm actually unfamiliar with high endgame content sooo) But I think we all already knew that stuff, it's kind of intuitive.

But as for my project of turning this into a TTRPG (and pointedly, avoiding the D20 "Sword and Sorcery" cludge) it seems my best option will be adapting a percentile, skill-based system such as Halogen, MERP, or even CoC. This will be mildly annoying as I have no experience with any of those, but never hurts to learn.

Thanks everyone for the input!