Experience Points

Experience points are not a new concept to roleplaying games. For decades, from the very beginnings of the the tabletop genre, experinence points, these intangible, metaphysical representations of learning and development, have been floating around, allowing characters to become better at doing whatever it is they do. ReD&D uses this same idea, because they're damned useful. However, rather than simply be something that is accumulated over a long period of time, slowly growing larger and larger, ReD&D goes with a modular approach; thus, experience points are spent to gain new abilities.

Why Experience Points?
Quite simply, "experience points," or XP, is a term that has been used for so long that even non-gamers tend to know what it means. As such, it is incredibly useful shorthand to get across the idea that these points make your character better. Rather than try to introduce new terminology (like how World or Darkness brought in the idea of "dots"), using a vague term like XP just makes things easier, both on the creators of this game and the players who come to play it.

Deciding on Prices
One of the biggest issues with creating ReD&D was balancing the XP cost of different things, such as vigor points, with other parts of the game, most specifically with skills and feats. Once those three were balanced, alongside ability scores, the game itself became much more stable. However, the real difficulty in assigning XP costs is with thematic abilities.

Thematic abilities are those essential little parts of the game that really add interesting options to characters. While anyone can invest in skills, purchasing thematic abilities truly differentiates one character from another. Supernatural abilities, unique abilities (like sneak attack) and more are all thematic abilities.

So, how are those things assigned experience costs? Well, it's a complicated process. The first part is finding out how often such an ability is likely to be used. If it can be used an infinite number of times per day, it's likely to have a high cost. If it can only be used once per day, then it won't have as high a cost.

Second, you have to take into account how useful such an ability is. How often it can be used is one thing, but if it overshadows another, otherwise useful ability, then it probably deserves a higher cost. If it's going to make another ability completely useless, then the price should be even higher (or perhaps the abilities should be altered to try and make them work better together).

Why no Levels?
Possibly one of the most obvious differences between ReD&D and most d20 systems is that ReD&D has completely abandoned the idea of levels. Or, rather, it has abandoned the D&D concept of levels. This is for a number of reasons.

First, while classes in D&D are interesting, they have a nasty tendency to reduce characters to clichés and stereotypes. Further, several classes are just completely useless when compared to others (see the many, many debates on how to 'fix' the Fighter or Monk). Fixing the classes is possible, and sometimes can be done amazingly, but it takes quite a bit of work.

Second, classes imply a certain natural 'tier' to characters. Higher level characters will, more than likely, be better at everything than a lower level character. In D&D, this is specifically aimed at combat. Yet, in literature, great combative characters are not necessarily skilled at crafting, and most wizened wizards can't go out into the wilderness and beat an owlbear to death with their staff. This disconnect between the literature and the game bothers many people.

Finally, classes are just a little bit too restrictive. When it comes right down to it, a Barbarian always gets angry and breaks things, a Druid goes and turns into swan's and rapes people, and Paladin's walk around with everyone hating them, because they hate everything. Prestige classes can expand on them, but they don't necessarily balance well, and they can be hard to create. And, this is not to say that some people, such as Paizo with their Pathfinder game, haven't made great strides in making classes more interesting and with more abilities. Others have done even better, such as the Ultimate Classes, but they still run into problems, such as when someone wants to play a Barbarian who can bind vestiges, or when a Sorcerer wants to manifest psionic powers.

For these reasons, and more that aren't quite as important, a modular system sets itself up as being a better alternative to represent a fantasy game. In the course of creating the ReD&D system, it has also set itself up to fix the problems with races (mostly with some being more powerful than others), make it easier to create monsters (and thereby make summoning and metamorphosis systems easier), but those are more icing on the cake than any intended reason for switching to a modular system.