I have been creating the idea of a RPG for almost 10 years now and recently (within the last year) begun my 7th version of it. The former versions were very short-lived and the product of a younger mind which I hope has matured enough to get down to the work involved. I plan to have this game playtest-able by summer next year and am currently building the foundations (races, class, mechanics, and rule sets). Since I looked around and saw people helping people with game ideas, this seem like the place to get the feedback and discussion I am hoping for.
I have a huge number of hopefully fairly unique ideas for this game but my utmost concern is to create a marketable product, so enough simplicity not to be a mess but elegant enough to carry some strategic depth. (any names I happen to use have been copyrighted btw)

The setting is a high fantasy world in which two factions each gifted with divine powers war with each-other for a lot of reasons, but mostly ideological differences in that one side believes the other is a bunch of insects that need to crushed, but enough with the fluff, onto the mechanics.

-basically d20 system.

-Follows the basic MMO dichotomy of tank, healer, striker, etc. but mixes up a few things for the purposes of action, pace, and fun. (For instance, one type of healer heals by AOEing. Her AOEs hurt the foes but heal the allies, and their is a tank that is supposed to tank by stealing the life out of enemies.)

-Uses the multiple defenses of 4E except AC is replaced by dodge and your armor acts as damage reduction. This is basically to allow the feeling that your armor is actually preventing damage when blows don't just glance off it harmlessly. (The amount of armor is kept fairly low so as to be a constant reduction but not a real downer by constantly reducing the damage by more then 4-5, basically making weak attacks misses, though the system takes care of this which I will explain later on.) 
I believe I will start with one of my basic ideas for a tank mechanic.

-Blocking is it's own mechanic which works as follows: Shield items have a block number attached to them like:    Buckler- +3 block, -1 dodge and reflex.
Say your guy has a dodge of 20 (19 with that -1) and wants to block. Take dodge without the negative (the negatives on shields don't apply while blocking, making you want to block with your shield when you have it. Making you rely on it more.) and add your shield bonus of 3 to it= so 23.  That is your defense against that attack. This seems like a sweet deal, and it is, you just upped your defense by 3 without doing anything. The downside is if that enemy should be able overcome your defense, they auto crit. If they don't, no damage.
This made all my friends eyes go wide when I say that, "But why would anyone every block" they say. I answer that firstly, shields can get some pretty sweet defense bonuses, up to +5 for the largest currently, secondly, I believe it's a question of risk. When you stand on the front line against impossible odds, is it more fun to slowly be picked to death by vermin or to mostly hold off the vermin and suffer a crushing blow from the boss? Narratively, I believe most might say the boss, because it's more epic. Speed wise, missed attacks are a hell of a lot faster in the long run. and fun wise, their is that moment of squinted faces in anticipation as the characters realize that a critical from the huge beast could mean trouble when the GM goes to make his attack.
This is the basis for that decision. Also to note, tanks will have enough HP to soak 3-4 crits from medium tough creatures, so the amount of 1 shots will be very limited.
Anyway, it's 1:00 AM and I am very tired. I have a lot more to post, I will be back later.

Have you considered that through sheer numbers the underlings rather than the boss will land that crit? In D&D once we had a rule that two 20's in a row means death (or was it three?)...a group of kobolds managed it on the palladin. We explicitly recinded that rule, as we realised the vermin would eventually take us down.

Also the block might just not be worth it - if you block 10 damage you normally wouldn't, but every fifth attack you take 60 damage from a crit, it's actually not worth it at all (except in small time sensitive edge cases).

On the other hand I think I get the idea of actually having a real result occur, instead of vermin just slowly nibbling. Significant events in battle, not just numbers slowly incrementing one way or the other. Perhaps instead of a crit the shield gets broken (and if you must keep the mmorpg tradition of 'gear is 4eva!', then it can be repaired after the battle)?

I realize the wisdom you are bringing to the table, but one thing I didn't mention because I was really tired and because it probably needs a longer explanation is that damage dealt in Obis is rather solid, meaning that you can sort of choose (and are often expected) to spend more of your turn on your attack to add a static damage bonus (this is a very important mechanic in Obis called Enhancing), making your damage rather steady. For instance, in Obis you would almost never roll 3d12 which would cause a massive crit, but rather have 1d8+12. A crit maxes out the roll, so 8 assured damage, and add a small bit more damage onto the top. So instead of 1d8+12 you would get a solid 24 damage strike. This would make more sense if I had the full time to explain, but basically crits are not going to be huge spikes of 50 more damage then you might have taken, but rather like 10-15 more damage then you might have taken. So suffering the risk of a crit is not as huge as it may be in D&D, while I still realize the merit of your argument, I believe it would be really annoying for your shield to be broken over and over again (also unrealistic if you have a really awesome shield, and magical shields would either suck and break all the time, or would be overpowered if they could never break) I know I could set a number of failed attempts required to break them, but that just another stat to worry about (and keep track of) and I am trying to keep bookkeeping to a min.
Also, I plan for block to rarely not be worth it. you would rather just take the hit and hope for a lucky dodge (since your dodge is reduced by holding a shield) then risk getting crit. I hope that though playtesting I find that this adds an extra layer of depth to what is usually a dry class type. 

Hi Roan,

Welcome to the Forge!

First, it's really helpful to talk about -what- you need help on for your game and what you're trying to do with your game.  Talking about the mechanics without any direction of what you need help on, could get you 100 responses - none of which are useful.  It's good to read the stickies at the top of threads, those have a lot of helpful guidelines to getting the most from the Forge.

Second, if your "utmost concern is to create a marketable product", you might be putting the cart before the horse, here.  Marketable product might not mean what you think it means- do you mean a game that people will play?  A game that will make enough money to be self-sustaining and earn you a little extra pocket change?  This is what we've seen successfully happen. 

Long term and lasting sales mostly relies on a good game, so that's really the thing to focus on.  The nice thing about D20 is that there are several D20 games which are still popular for play, not necessarily based on "something new coming out!" fervor- so you can look at what they did with D20 and what has worked well and consider that in your game.

1.  Do you have specific questions/issues that your system needs help or input with?
2.  Is it mostly done? Have you playtested your game in this version?  Have other people who haven't played with you, playtested it?

Chris

Hello, thanks for the welcome Chris, sorry for not reading all the stickies, I was rather excited when I first saw that their was actually a forum for RPG design after months of plodding along alone, so I just kinda jumped into it. I will rectify that mistake. I have not tested this version of the game yet and am hoping to do so soon. I will switch forums when I do.

One more question for you Chris, if I do play-test one idea but create another, can I post that new idea here still or should I stick over in the other forums?

As to why I made a note of my attempt to create a marketable game, I was just hoping to denote that I am serious in my efforts, and any help I am given will not be wasted in a month when I quit.

As to what I need help on: My game assumes you are using a board or miniatures to keep track of distance and battle. 
My system of combat is point based. Each round (the amount of time it takes for each creature involved in combat to do one turn worth of action) a creature is alloted 5 points which they can spend on their turn to perform actions. Their are three types of actions a character can take within combat:
               
Movement- Each movement action takes 1 AP, The average movement is 3 squares. A character can perform two movement actions per turn.
               
Striking- A striking action can take varying amounts of base AP to perform, swift attacks from daggers to long-swords take 1 AP, larger weapons like a claymore take 2 minimum. In addition to the base AP you pay to perform a striking action you may pay additional AP to increase the damage by an amount determined by the weapon or special attack, this is called Enhancing. All weapons and most special moves have an Enhance, and their are going to be a few different types of enhance. The most common is Enhancing by statistic, written like (Strength 4), this means that for each additional AP you spend on enhancing this attack you may add your strength modifier to the damage, but no matter how high your strength modifier, you are capped at 4.
        Example: Long Sword- 1d8    Enhance: 3 strength  Base AP: 1     
-You spend 1 AP to swing with this long sword, if it connects you are going to do an auto 1d8, but now you have the option of enhancing that attack by spending any amount of your remaining AP to increase the damage by up to 3 for each AP.
This is intended to feel like the character is putting more force and time behind their strikes, causing varying degrees of damage depending on how much AP you can spare. It can also allow easy many-turn charging, such as the casting of a long spell. Setting an AP, such as 15 to be built up over multiple turns, and then the long spell is cast. You can only perform 1 striking action per turn.

Other- You can perform a non-striking, non-movement action such as drawing a sword or drinking a potion as many times as you can pay AP for them. The cost for these simple actions will most likely be charted, and most of them will cost 1 AP.

My question to you all is: Is this too complicated to be swift in play with understanding that this is just a few of the rules of combat? Is this all understandable or is it hard to grasp? Finally, if you do believe this is acceptable as far as level of complexity goes, do you think it will be fun for players?

Hi Roan,

It's best to think of it as your game as a whole and not separate mechanics.  If you playtest your game, and then change major portions of it - you'd still post in the Playtest forums.  You'll find, though, that a lot of the problems you think you might have vs. the problems you REALLY have, come out in playtesting.  Or, more importantly, the trivial problems you can solve ahead of time, the sticky problems that aren't easy to fix come up in playtesting.

Your actions for points system, at least in summary, seems very straightforward and a lot easier to digest than, say, D20's massive list of Full, Standard, Move, Immediate, and Free actions (which, I had to tutor several players through and they never really got the hang of...).

The nice thing is that you can take advantage of lessons learned by other games in terms of how to best handle crunchy mechanics like that- you can start putting together your own "Action Cards" for different weapons or spells, so when people are playing, they can have it right on the table in front of them - "Oh, if I use the longsword it's going to have this much AP but do this much damage, but the knife gets these bonuses... hmm."

Don't worry too much about whether your game is "too complex" for a hypothetical crowd at this point.  If you have a solid system in place where people could play the game (even if you don't have character creation, all the weapons or spells or skills or whatever in place), it's a good time to start. 

The sooner you find what works and doesn't work within the core of play, the less work you'll have to do re-fixing things- for example, you may find that you have to change your action point costs... you'd rather do that for 10 weapons than a list of 100 weapons, 50 spells, etc.

Do you have any design issues blocking you from getting it to play yet?  Or things that are completely leaving you blank?

Chris