It boils down to the idea that a little change goes a long way. Conan presented too much change for fantasy gaming for our group. Really, d20 D&D does fantasy gaming very well. Conan would have done better for us had the game decided what few changes were really necessary to bring out the flavor of the genre and go with those. Making everything new & different was just too much for us.
If I were to run a Hyborian game, I would be more prone to do it with the basic d20 engine with a few changes to make it more like the novels.
The Hyborian Age presents rules alterations to standard d20 D&D to make things a bit more Conan-esque.
I would say that even though d20 Conan does change many rules the core remains the same and most rules changes are not so far removed from the SRD.
A deconstruction.
Character creation and advancement remains essentially the same. The minor alterations to ability score increases, hit point accrual and bonus feats are in place to make the character on relatively equal power with D&D counterparts of similar level in a setting where personal magical power, in the form of magic items and buffing spells, is not as common.
Races are all human variants. The only really different rule that is a function of race is the Favored Class mechanic which does more solidify the archetypes of the race than anything else.
Classes are different but very recognizable. Most are simply variants on the standard barbarian, fighter, ranger, and rogue. I would say 80% of the class features are identical or at least analogous to class features a D&D player would be familiar with. The biggest departures are the Scholar and the Temptress both of which are spell using classes and draw upon the heavily altered magic system.
Skills and Feats are no different in implementation than the SRD. There are some feats that have effects that interact with the alterations to Combat and Sorcery systems but feats are feats and skills are skills. There is no difference to how they are acquire, rated, or used.
Combat is the second most altered system after magic. The immediately notable differences are the loss of Armor Class and the inclusion of Damage Reduction as the benefit of armor. These changes do produce a cascade of changes mainly in the interpretation of how you are defending yourself (Dodging or Parrying) but also in the manner you attack an opponent. The definition of Finesse carries more weight than in D&D.
I think that most of these rules do serve to represent the feel on the genre and setting. Armor becomes important to combatants but not a must-have of the standard adventuring kit. This serves to preserve the 'sword-and-loincloth' feel so common to Howard's stories but still makes armor viable and useful.
Additionally combat has a variety of maneuvers available to give characters with the proper (and as I stated earlier sometimes punitive) prerequisites the option for some pretty Conan-esque options.
Decapitate and
To the Hilt come to mind.
These are just layers that overlay the standard rules. The armor and defense rules are a major departure, yes, but the remainder of the rules (actions, movement, grappling, attacks of opportunity, etc.) are all derived from and identical to the SRD.
Magic is the major change in Conan and is no where near the Vancian system of D&D. I won't go into too much detail but sufficed to say sorcerers are no longer mobile heavy weapon platforms and bottomless utility kits. I think of all the new rules the Sorcery chapter is the best representative of the Hyborian age.
One of the major issues with Sorcery and the spell-using Scholar is that it is not as viable a player character in the beginning. The spell selection is woefully limited and usually serves only as a minor buff/debuff or other low grade interferences. Non-combat magic is more useful and powerful but separates the sorcerous character from the action of the other characters. Alchemical preparations do a bit to level the field but they are notoriously expensive to prepare and sometimes a bit harsh in their consequences to the target, many being save or die essentially.
If one wishes to play a spell-caster than it is important to be prepared for a long laborious road to power
OR take the path of the multi-class dabbler and use sorcerous magic as an augment rather than a focus. I find both of these options to be well reflective of Howard's writing.
All in all I don't think that d20 Conan is as much a departure from standard d20 as other game. While not as recognizable as something like Midnight or the aforementioned Omega World it is still closer than True20, Mutants & Masterminds, or Spycraft. And yes the last two represent very different genres but when the fantasy books for either arrive they are going to look a lot different than D&D, I would imagine.
Ultimately my point is that the system mastery issue of d20 Conan is not nearly as prevalent to my eyes as others might suggest. The minor sub-system changes to combat are, IMO, a better representation of Howard's writing and the magic system can be easily reserved for NPCs, and in some campaigns should be, if the GM is going for the freebooting rogue theme so common to the stories of Conan and the Hyborian Age.
