Hello,

I've been working on creating an fantasy rpg to play.  Not interested in publishing or anything like that, just want something friends and I can play. 

I'm starting with a D&D base and adjusting from there because that is what I know.  I played AD&D as a kid (I'm 33) and recently developed an interest in playing again but after reading 4E and even 3.5 I was not really satisfied with the rules for various reasons.

I need help in organizing and putting things together.  I have several thoughts but nothing is unified.

What I have so far in no particular order

All PC's will be humans which will be the most common race.  Population ratios will look like this.  10,000 Humans : 10 Dwarves: 1 Elf : .01 Dragons

Humans are a relatively new species but the world is very old with the other above races once be prominent and in power but now in decline, this allows my world to be very old and worthy of exploration.  PC's will generally be explorers out to strike it rich ala the Wild West, or Bandits, outlaws, etc

PC abilities will be the following
1.Strength - ability to lift, carry and do damage
2.Dexterity - Hand Eye Coordination & striking , Aim
3.Athleticism - Agility, Jumping & Running, Foot Speed
4.Constitution - Hardiness, Fortitude, Endurance
5.Intellect - ability to reason, memory, learn skills and magic
6.Persona - Common Sense, Will Power, ability to lead and influence others, ability to handle stress or surprise, and instinct

I like the idea of separating out the ability to strike something from doing damage to it.  This mirrors boxing for example where Floyd Maywearther would have a high Dexterity but a low strength compared to Heavy Weight Fighter and I don't at all like associating that with running, dodging or other athletic feats.

Instead of scores (1-18 etc) abilities will be expressed in terms of modifier +1 for example and in general means 25% greater or worse.  So for example someone with +1 strength is considered 25% stronger than someone with 0, someone with -2 intellect is 50% less intelligent than someone with 0.  PC's start with 2 +1's, 2 -1's and 2 0's of their choosing with a undermined additional bonus to then be added.  Something like 3 - 7 points.

All rolled events will be determined using this formula which is the standard D&D formula.

Chance + Ability + Skill + Magic + Environment

The one big change is that instead of having chance equal 1-20,  I am going to use 1-30 because I like the idea of modifiers equaling only 3% instead of 5% as I am hoping this will create a longer lasting "sweet spot"

I also am going to combine the to hit and damage rolls using this formula

Where attack roll is > defense

((Attack Roll - Defense)/Defense )* Base Damage

so for example Zed the warrior attacks an Orc with a Physical Defense rating of 16 with his longsword

He rolls a 17 and has +3 in modifiers for a total of 20 for a hit.

20 - 16 = 4: 4/20 = .2.  The base damage for a longsword is 10 and Zed has +3 in modifiers (75%) which increases it to 18

18 * .2 =  4 Damage

I'm sure this seems very complicated but I've created spreadsheets using macros which do all the calculations.  I like this because it adds a degree of damage based on how well a foe is hit.  Additionally I like using % modifiers for damage because I didn't like the idea that a modifier of +1 would be equal for a broomstick and sword for example. 

That is where I am stopped right now.  Would be interested in discussing the above and where to go to next.

My big questions now are

How will defense work?  I like the idea of different defenses similar to D&D 4e.  Once I have this I can playtest some combat.

I also have not decided what classes there will be.  I think I am leaning towards a system of trade offs rather than strict classes

for example you can wear armor which gives greater protection but doing so restricts movement and restricts or prevents the casting of magic.
You can choose to increase your skill with the sword but doing so forgoes the other possibilities.

Basically I want a barbarian for example to be the representation of a progression of choices rather than a strict class based on 1 initial choice.

However I don't really have an idea on how to map this out

This seems like a lot of crunch come combat time. Especially as characters get to high levels, attacking multiple times per round, there's going to be a lot of calculation and slowdown, which might be harmful to the flow of gameplay. I felt like AD&D had the same problem as far as complexity, but complexity isn't necessarily a bad thing. You're going to have to rely on your macros and such to keep the game running at a reasonable pace, and personally I don't like staring at a screen during game any more than absolutely necessary.  The idea seems ok, it's just crunchier than I would go with it.

The idea of different defenses is a great one, and definitely one you should go with, I think. Heavy armor might help against a sword, but might not be any good against a fireball. You could break up defenses into tough/reflex/will, essentially. Toughness would be your ability to shrug off the hits (armor class), reflex would help you avoid damage from fireball/lightning bolts etc, and will would let you resist charm/sleep/fear. Just a thought about defenses. Fortitude as it was presented in D&D doesn't seem that necessary, you could roll it into toughness if you liked.

If your going to go the standard "big system" fantasy route, you're better off "sticking with the game" and basically coming up with house rules.  The reason is, if you get too far off course, you have to *REMAKE* everything your want from D&D to fit your game. This is a *bad bad* course to choose. Instead, let me make some suggestions that'll help what you want accomplished.

If you want high magic, you *need* to let your melee characters use Tome of Battle, or else they get completely overshadowed by the casters.
If you want low magic, delay the spell progression. Characters should have about level 3 spells at level 7 and then slow it down even *more*, and ban other spells outright.  While you slow down what level characters get spells, you should still give them more spells to cast each level or give them martial ability (I'd do the latter.) 

Change the spell casting so the caster rolls against the defense (add 11 to all the saves, and treat as AC, subtract 10 from all spell DCs and roll them instead.)

The rest can just be applied as a homebrew setting.

Next, if you are determined to come up with your own system, here's my advice.  First of all, read the article "Fantasy Heartbreakers" http://www.indie-rpgs.com/articles/9/. Finally, here's my other suggestions if you go ahead with this anyways.

1. Stats... have you thought about removing these entirely?  Nearly every system has them (including my own), but I feel you could better accomplish your goals with a smart skill list, and the right "perks" given by classes and chosen by the player. 
2. Also, I'm not a real fan of your stats, they don't really make any more sense than D&D stats, they just have your own slant to them. I kind of like Tri-stats method, it gets the clumsiness out of the way (Body, Mind and Spirit are tri-stat's stats.)  Simple is better than complex in stats.
3. The modifiers bit is smart.  I think the only reason D&D holds onto this is because it is the way it has always been done... but it is definitely one of the most misunderstood bits of the game.  Even in 4th edition, they kept the clumsy system, even though they butchered the holiest of holy cows (magic missile.)
4.  The dice you use for probability doesn't really matter if your system is built right.  What breaks D&D at certain levels are A) spell casters and the martial classes inability to keep up B) hit points C) IDIOTIC save and initiative progressions on monsters and characters D) set DCs for tasks
5. Here's an *alternate* and simple way of combining damage and attack rolls that I came up with. 

roll attack vs. AC, find the difference (21 attack against 15 AC = 6)
add damage bonuses to the difference (+5 damage + 6 "excess hit score" = 11 damage)

For defenses, I would truthfully stick to having different static scores, like 4th Ed, with armor giving a bonus to AC.