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Open Game License d20 System

Updated on June 24, 2010

I recently had opportunity to run a short-lived D&D-style campaign for a small group of young players. Since I haven't played or GMed D&D for over a decade, and have no resources on hand, I went searching for a basic low-cost game system. I discovered the Open Game License d20 System, published by Wizards of the Coast. As far as I can find, this system emulates D&D 3.5 rules. The last time I played or DMed D&D was under 2.0 rules, so I had some work getting up to speed for my game. After studying the rules intently, and running that short campaign and another ongoing small campaign, I have some criticisms of the system.

Action System

I find that the action rules are more complex than necessary. The d20 system uses four types of actions: standard actions, move actions, full actions and free actions. Within each action type are various possible actions any character can take, from movement to attack to speaking a few sentences. There are occasions when a move action can become a standard action or part of a full action, or a standard action can become a move action, and so on.

Because a move action and a standard action are about equivalent, a simpler system would be to allow three action types- free, simple, and full. A list of what actions are allowed within each category, and a few limitations on movement and attacks, would suffice. This kind of change would have a simplifying effect on gameplay, especially for young or new players. This change would entail the rewriting of the Improved Feint Feat. Instead of becoming a move action, an improved feint would become a free action. The Rapid Reload feat does alter the action used to reload a crossbow, but no rewrite would be necessary under this change.

Weapon Proficiencies

I also find that the weapon categories are much too broad. All available weapons are categorized as 'simple', 'martial' or 'exotic'. According to the documentation, the fighter class is proficient with all simple and martial weapons. I find this to be ludicrous. These two lists include weapons such as a dagger, greatsword and halberd. These three weapons require vastly different styles to utilize effectively. This is without mentioning the two dozen or more additional weapons in those two categories or the weapons allowed to other classes. I have trouble believing that a level 1 human fighter, age between 16 and 21 years, is proficient with all that variety of weaponry. This is just not a realistic situation. A level 1 elf, age between 116 and 146 years, could easily have that knowledge and ability, but not the human.

Better would be a weapon proficiency skill with variable points based on class and perhaps race. A fighter might have enough points for a half dozen weapons, all with respectable ability, while a wizard would get perhaps two weapons, at the lowest possible ability. Also, different classes would be limited as to which weapons and types of weapons could be chosen. I know that this change seems very 2.0, but that system made more sense.

Another fix might be to categorize the weapons into similar types, such as polearms, axes, blades, or other categories. This would allow weapon proficiency feats without overloading any class or race with unbelievable ability.

Attacks of Opportunity

I wonder if the creators of the d20 system actually thought through this feature before writing it as they did. According to the documentation, a character engaged in combat for 1 round (about 6 seconds actual time) can engage a chosen target while at the same time attacking another valid target of opportunity. I have had some basic sword training in my life. The idea that I can engage a combatant with a weapon, while at the same time attack another target, all within the space of 6 seconds, is not realistic. On top of that, there is a feat which could enable that same combatant to engage his chosen target plus up to 4 or more additional targets, simultaneously.

A better writing of the feature would be to allow either attacks of opportunity or regular attacks, but not both, in 1 round. Either an attack of opportunity or a regular attack would require a simple action. Attacks of opportunity would still be allowed against the chosen target, but not any other target within reach. The Combat Reflex feat would still allow the extra attacks of opportunity, but not along with a regular attack. This feat might work well for an invisible rogue in a crowded melee.

There are eleven feats affected by the attacks of opportunity rule, but the only one that would require rewrite has already been addressed- Combat Reflexes. The other ten would function fine as written under such a change.


Within the D&D systems, Charisma has always been the least used ability score. When I played Bards under 2.0, charisma was quite useful for gaining followers. There were a few other uses for charisma, but compared to the other scores, it was lacking.

Now I read in the d20 system that both Sorcerers (new class) and Bards use charisma as the basis for their spellcasting ability. I'll bet the creators of the system were trying desperately to find more uses for charisma, so they created a new class and rewrote Bards to accommodate their goal. The idea that charisma regulates spellcasting is hard to swallow. If you want a spellcaster that can rip off any spell she knows without prior study, fine. Just don't insult your players by basing that ability on charisma. Intelligence as a basis for spellcasting works fine and makes the most sense.

If you still want your Sorcerer class, work in some limitations to balance her abilities. A required magic school focus or a stricter limit on the amount of spells usable per day would help to balance such a class. As for Bards, stick to what makes sense- intelligence as a basis for spellcasting and charisma as a basis for performance skills. I know that you can now use a Leadership feat to gain followers, but why not give that feat to Bards as a bonus feat, say at level 6 or so, after the Bard has had time to establish a reputation in a city or region. That feat uses charisma as a modifier. Allow the Bard to gain followers before level 10 and you've given charisma a more positive use in the system.

If you really need more uses for charisma, create a class that uses charisma in a way that makes sense. This may be difficult, and I am still working on it.

Positive Aspects

Many aspects of the Open Gaming d20 System are positive. The system is free, which is the best price. The spell list included is quite extensive, for both arcane(wizard) and divine(cleric) spellcasters. If you want to run a high-level campaign, both paragon (levels 10-19) and epic (levels 20-30) rules are included. There are psionic rules, divine rules, and variant rules from the Unearthed Arcana material. Feats were not available in D&D 2.0. I find the feats to be a creative addition to the system, allowing characters more abilities and players more choices of abilities.

Although an experience point (xp) table is not included, creating one is quite simple using the following formula. L =target level; XP=experience points; XP(L)=0 if L=1, else XP(L)=XP(L-1)+(XP(L-1)*1000) This is a base 1000 xp table. You can easily change the base for either higher or lower xp requirements. If you want a base 750 xp table, substitute the value 750 for the value 1000 in the formula.

The d20 system can be found at this eddress:

Once again, all the info is free. You are free to develop what you like around the system, so long as you include the license agreement with anything you distribute to players or fellow DMs. The license documents are included on the site and with the download.


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      jason szewc 

      6 years ago

      i am a retired naval nuclear propulsion engineer i have worked in conjunction with bettis lab as well as lockheed in martin i have the well wishes of the starwars d20 gaming system as seeing i accidently by no fault of my own would be willing to create along side a colleague please contact me at gronkie2001-2003. yeah i enjoy almost anything. i find some games limited and binding and would like more of a seamlined approach to gaming where a laptop is integral. i see big opportunities in the advanced side of things without the pens and paper. but hey lets not put the cart before the horse im reading through your ideas and i find a charisma based enterprise to be something as i lack some aspects ? and also am soft spoken but easily assertive. there has always been a line of open friendship and i see this as a true friendship look grizzled on the outside sort of you know dont mess around but when i speak people laugh and go i just dont believe it because every day im shuffling. love magic hearts and spades


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