First of all system used in Pillars of Eternity should have a name. Back in 90's all RPG systems had names. The same was in case of cRPG, like Fallout and its funny history of name ("ACELIPS") becoming S. P. E. C. I. A. L.
RPG mechanics used in Pillars are well designed so I would vote to use them, only slightly changed. The biggest problems are percentages damage bonuses and percentages benefits from attributes. It's hard to count this type of numbers during RPG session. Percentages should be replace to constant values. But it will require balanced values and it'll be extremly hard.
I'm working on something similar, so hear me out.
I was adapting Star Wars Saga Edition (d20) for Mass Effect setting since 2010. A while ago I changed RPG mechanics for system used in Pillars of Eternity and it's even better for this purpose. Miss, graze, hit and critical hit all have compartments and they are brilliant for Mass Effect when comparing them to lore of the setting. For example, upgrades like "biotic damage" from ME2 are describe as software increasing accuracy of biotic powers. So increasing accuracy increase damage and this is exactly how attacks work in Pillars of Eternity. The better accuracy you have, the more chance to actualy succesfully hit, diminishing chance for graze and increasing chance for critical hits - in all cases you will do more damage. So why d100 instead of d20? It's more precise. I could divide all numbers by 5, then it would looks like 1 - miss; 2-10 graze, 11-20 hit, 21+ critical hit but it woudn't be as precise as d100 and its 1-15 miss, 16-50 graze, 51-100 hit, 100+ critical hit.
Attributes work well with impact on four types of defense stats (deflection, physical force, dodge, will). Equivalent of Dextirity get cooldown bonus instead of reduced time of recovery action (which woudn't work in turn based combat). I redefine other attributes - like Strength reducing weapon's recoil, Constitution bring limits for using biotic powers before character moves down on exhausted scale (it's concept from Star Wars Saga, 5 grade of penalties from debuffs or bad condition) or until character rests. Other benefits from attributes are the same as they are in Pillars, but adding constant value instead of percentage.
I see that character development can be a challenge because I like the idea from Star Wars Saga - 3 or 4 groups of talents for each class. It's Mass Effect so there will be combat, tech and biotic powers and I want to use feats. So it's hard to plan how or rather when a character will learn all three types of special abilities while leveling. It was simple in Star Wars Saga - bonus feat on each uneven level, bonus talent on each even level. But in my design there are 3 types of abilities to pick - class talents, powers, feats.
Another matter is skills system. Pillars of Eternity has specific system which require certain skill to pass difficulty check, while there is no random number generator. Skill level has to be equal or higher than DC. It's logic but I'm not sure if this will produce a fun factor in real RPG session - knowing that you can pass the check without risk. And skills from Star Wars Saga gave my great ideas how manage hacking, explosives, stealth, piloting etc. but I'm not sure if it will works good enough based on d100 mechanic. Good design require consistent system for all tests.
My system adapts damage reduction (because of shields and the way I designed health) from armor, shields as equivalent of endurence from Pillars of Eternity but health will have a very low value to allow kill in one or two attacks. Armor will be destructable and repairable and when your shield go off your armor will be the only thing between you and death. So some powers and ammo type will have option to destroy armor (striping character from damage reduction) and there will be weapons with better armor piercing stat. And ofcourse - there will be cross class combos. CCC are now so popular that we will have fun with them even in Tyranny ^^
So yeah, Mass Effect. It's not offtopic. I mean, if I can convert system from Pillars of Eternity for need of sci-fi tabletop RPG, I think it's doable to adapt game mechanics to pen & paper version of this one specific, beautiful designed game which Pillars of Eternity is.
Edited by Silvaren, 12 October 2016 - 01:15 AM.