Property-based RPG System

[soggie]

RPG Codex Acid Test Time:

I've created a very simple non-floating point based RPG mechanics and hopes for some criticism.

The system is property-based because it makes no distinction between skills and attributes. There are 24 properties grouped into 4 groups:

1. Combat
Sidearms, Light Firearms, Heavy Firearms, Explosives, Unarmed, Melee Weapons

2. Social
Intimidation, Persuasion, Deception, Leadership, Insight, Haggling

3. Utility
Fieldcraft, Medicine, Crafting, Security, Engineering, Science

4. Attribute
Strength, Speed, Stamina, Perception, Willpower, Memory

Each property has a range between 1 to 10.

ALL actions in the game generates challenge rolls, which works like this:

Challenger Level = 1 to 10
Resistance Level = 1 to 10
Modifiers = -7 to 7

Base Challenge Level (BCL) = Challenger Level - Resistance Level = -9 to 9
Normalize Challenge Level (NCL) = BCL + Modifiers + 17 = 1 to 33
Success Rate = NCL x 3 - 1 = 2 to 98

Modifiers include things like stress-level of situations, whether the challenger is hurt (which reduces efficiency) or not, what equipment is he using, and a host of other factors that provide penalties or bonuses. Modifiers are further split into two quotas: (1) Efficiency mods and (2) External mods. Efficiency mods are determined by the state of mind of the initiator of the action (wounded initiators suffer penalties, high spirited initiators gain bonuses); while external mods are mostly environmental modifiers (terrain cover, weapon bonus, armor bonus, etc).

Once the SR (success rate) is calculated, a D100 die is rolled against the SR. Anything lower than the SR is considered a successful challenge roll.

Here's an example of picking a lock in a combat situation:

1. A is picking a lock in combat, after sustaining a wound in the shoulder (-2 under combat sit, -3 shoulder wound)
2. A has 6 in lockpicking
3. Lock's resistance level is 3
4. A is using a master set of lockpicks (+3 lockpick)

BSL = CL - RL = 6 - 3 = 3
NSL = BCL + Mod + 17 = 3 - 2 + 17 = 18
SR = NSL x 3 - 1 = 53

Therefore A has a 53% chance of succeeding the lockpick attempt.

So, every task in the game generates a challenge between two properties. Trying to shoot a guy behind cover with a pistol invokes a Sidearm vs Fieldcraft challenge with shooter HP as an efficiency modifier and terrain cover as an environmental modifier.

What do you guys think of this kind of RPG system? I like its simplicity and universal nature. But I'm just a n00b when it comes to designing RPG mechanics. Criticism is greatly appreciated.

 

[rpgcodexusername]

quite nice, but i would make attribute scores 1-100 so the player can improve his skills slowly

 

[soggie]

quite nice, but i would make attribute scores 1-100 so the player can improve his skills slowly

I had a previous system that runs from 1 to 150, but the problem is I needed to multiply it with 0.25 to normalize the skill challenge range to 5 to 95%.

BSL = CL - RL = -149 to 149
MOD = -51 to 51
NSL = ( -200 to 200 ) + 201 = 1 to 401

SR = NSL x 0.25 = 1 to 100% (rounded down)

While a computer might not have any problems performing such a calculation, I figured it's unnecessarily complex and kind of goes against the KISS concept I had when designing the system.

Also, I avoided floating point multiplication to speed up the calculations because in the game, there are many checks almost all the time. Every step a character takes triggers a Perception vs Fieldcraft challenge to determine if he had been heard by a nearby enemy. Multiply this by the number of enemies in the immediate area, and you'll get a lot of calculations going on at the same time.

Besides, personally I think giving them a range of 1 to 10 makes every increment seem more worthwhile and effective. 10% increase vs 1% increase.

What do you think?

 

[GarfunkeL]

Seems simple and effective enough for P&P.

 

[Orgasm]

Also, I avoided floating point multiplication to speed up the calculations because in the game, there are many checks almost all the time. Every step a character takes triggers a Perception vs Fieldcraft challenge to determine if he had been heard by a nearby enemy. Multiply this by the number of enemies in the immediate area, and you'll get a lot of calculations going on at the same time.

Im interested. How big is the difference?

 

[soggie]

Also, I avoided floating point multiplication to speed up the calculations because in the game, there are many checks almost all the time. Every step a character takes triggers a Perception vs Fieldcraft challenge to determine if he had been heard by a nearby enemy. Multiply this by the number of enemies in the immediate area, and you'll get a lot of calculations going on at the same time.

Im interested. How big is the difference?

Admittedly, the difference is negligible. It just gives me a peace of mind when I am implementing complex composite real-time challenge rolls (like performing a stealth backstab at one of the two guards posted along a dimly lit corridor which requires the player to traverse it in order to reach the guards in the first place).

I guess the major reason why I kept it in integers was because it's much easier to test and prototype on paper (and easier for my puny brain to perform all the mental calculations without the need of dancing my fingers on a calculator).

 

[J1M]

Unless you are modeling each individual dust particle you won't notice a difference between integer and floating point math.

EDIT: Actual feedback

1) Most people intrinsically understand that higher roll = better. Your system breaks this and could be changed pretty easily so it wouldn't.

2) How would you handle something outside your 24 attributes? For example, seduction. You might want to build in rules for combining more than one base category to create a check. For example: weight + constitution = alcohol tolerance. (Or in your system strength + stamina)

 

[crufty]

what if

NSL = BCL*10 + Mod*10 + 17


right now it seems like mods don't have enough impact so why bother?

re lockpick ex:
3 v 6 = 50%
all that calculation ~ 50%

also instead of realtime what about blocks of time: every15 minutes roll the check. this would give some tests more meaning.

 

[Lord Rocket]

the KISS concept I had when designing the system.

OK first of all dude, you shot that in the head when you decided three separate calculations were necessary to obtain your actual target number. Including multiplication, addition, and subtraction. You're obviously targeting CRPGs with this (frankly it would be far too slow to play in P&P. Personally I'd say that suitability for P&P is the gold standard for simplicity in RPG systems design) and as such there's no reason why you can't go nutso with the number ranges.

Let me guess - you've played Fallout quite a lot but not that much P&P?*

Right, anyway, I did a couple quick calculations and didn't like what I found very much. TLDR verdict is: needs work.
First of all, since the system is completely linear, there's no difference between a competition between a skill 3 person and a skill 1 person, and a skill 6 person and a skill 8 person despite the fact in the first example the latter chappie is only a third as good as the former while in the second, the latter has, proportionally, a much lesser advantage. To some degree this is a preference of mine (I like bell curves and things like that when I roll dice) but I think it has some merit.
Second, despite crufty's statement that mods don't matter much, your attribute levels** don't either. Consider this competition: Cedric Soft (strength 1) vs. our old friend Burly Bob (strength 10). They're arm wrestling as this is what Burly Bob does.
If the PC is Cedric Soft, then we have a ~24% chance of victory, right, assuming Bob isn't hurt or anything like that. That doesn't seem quite right to me. Burly Bob gets the converse (~77%), which seems rather low considering how much he outclasses Cedric.
You could handle this, I suppose, by making every opposed test of this sort 'best of three,' but honestly I'd fix the problem at the root instead, especially if you're keen to KISS it up.
Thirdly, as you've probably realised by now, a 1 point improvement in an attribute is hardly a 10% improvement.

Another thing - I don't think that using opposed rolls for all combat or conflict is necessarily a great idea. Your example of pistol vs. guy in cover for example - am I, who knows nothing about outdoorsy shit, really any worse at crouching behind a big fuck off rock than my dad, who loves that sort of thing? What if there's a sniper aiming at a dude who's standing still in the open? There's no 'being a big fat target' skill, what's the sniper rolling against?
Actually on that note I've been trying for about a year and a half to find a way to justify separating flat difficulty numbers (ie. the sort of thing they use in DnD or your Challenge Rating thing) from difficulty modifiers. Enlighten me?
(Take the sniper example above. Since his target's just standing there eating licquorice or something and being all oblivious*** then presumably the sniper's going to be rolling against the range or something. Why is that more/less important than wind speed/direction or the target's skill at dodging - which would be the biggest factor if fatty knew the marksman was there?)

1) Most people intrinsically understand that higher roll = better. Your system breaks this and could be changed pretty easily so it wouldn't.

Sigh. Although number 2 from the same post is a pretty decent bit of advice - you definitely need to get some synergy going.

Anyway I think this post is probably a bit harsher than I meant it to be. Sorry about that, but I'm going to go fap now so I'm not going to change it.

* That probably sounds sarcastic, but it's not supposed to be.
** Property? Don't make up new jargon please, especially since putting attributes on the same scale as skills and disassociating them doesn't really change what they are in any meaningful way.
*** Ha ha ha I made an Oblivion joke.

 

[crufty]

fwiw treating attributes and skills as the same meta-data is a good strategy

i also think one thing that can help is using 10d10 (where d10 = 0 ... 10) clamping 0 to 1

1d100 or 1d10*10+1d10 have a lot higher chance of 100 or 1....

 

[soggie]

Alright, back to the drawing board for now. I'll be back.