The Sweet Spot

My ongoing House of Worms campaign uses the 1975 Empire of the Petal Throne rules. As you probably know, these rules are perhaps one of the earliest examples of Dungeons & Dragons house rules ever published. That is, on a fundamental level, EPT is not merely compatible with but wholly derivative of OD&D, at least when it comes to game mechanics. Take a look at the combat matrices, to cite just one obvious example, and what you'll see is identical with what's in Men & Magic. This is not a criticism and it's this continuity with the mechanical conventions of OD&D that make Empire of the Petal Throne the hands-down best choice for introducing newcomers to M.A.R. Barker's world of Tékumel.

At the same time, there are many, many divergences from OD&D in EPT, some small, some large. Among the bigger changes are the way the game handles experience points and leveling. Take a look at the two charts I've reproduced in this entry. Section 630 includes the XP charts for the game's three classes: warriors – here called "fighting men" – priests, and magic-users. This reproduces pre-Supplement I OD&D. A close examination of the particulars reveals differences. Priests requite more experience points to level than do OD&D clerics, while EPT magic-users require less than their counterparts. What you'll see is that, for the most part, all three EPT classes use the same XP charts, that of the fighting man from OD&D (though, interestingly, EPT magic-users need fewer XP than the other two classes at high levels.

Experience points in Empire of the Petal Throne are obtained

in only two ways: (a) acquiring treasure (gold – or other items which can be exchanged for gold Káitars), or (b) slaying hostile beings. No points are granted for casting spells or other types of activity.

This is identical to the approach of OD&D. A key difference is that EPT opponents are only worth 50 XP per hit die rather than the pre-Greyhawk value of 100 per hit die. There is no consideration of the difference between level of character and the level of the monster for this calculation as in OD&D. On the other hand, EPT awards XP on an individual basis, with the character who delivers the killing blow being the one who gets all the experience, regardless of how little damage he might have done. (This is a rule I do not use in my House of Worms campaign) 

This brings us to Section 620 above, which introduces another change from OD&D. Rather than looking at the relative difference in level between a character and a monster for determining an XP award, Barker instead introduces a blanket reduction in XP gain from all sources, starting at fourth level. This reduction increases by steps every two levels thereafter, until, at tenth level, a character counts only 5% of the XP gained toward his advancement.

Taken together, all of these changes, big and small, to the OD&D approach to experience points produces something that, in my experiences, prolongs the "sweet spot" of play. While there's disagreement over precisely where the sweet spot lies, there seems to be a widely held belief that there are a range of levels in D&D-style gaming that are the most congenial to the right balance of risk versus power. For me, that sweet spot lies between fourth and eighth level, when the characters are sufficiently durable that they can't be felled in a single attack – though, it should be noted, Empire of the Petal Throne has an "instant death" critical hit rule – and yet aren't so potent that death is so far from a possibility that they don't act with caution.

It's quite fashionable in some circles to dismiss XP only for defeating enemies and treasure as retrograde, silly, and un-fun, among other things. To the contrary, what I have found is that, because the characters in the House of Worms game – and, I would suspect, most long-running RPG campaigns – are not forever delving in the Underworld and looting tombs, the rate at which they gain experience points is slowed. While lately the characters have been engaged in the exploration of the Temple of Ages and facing off against its denizens, there have been long stretches of the campaign where they were instead involved in diplomatic negotiations, murder investigations, historical research, marriage arrangements, etc. Weeks or even months have gone by without so much as a twenty-side die being rolled in anger. 

If XP were awarded for "roleplaying" or reaching "milestones" or some other activities, the characters would have amassed more points than they have under the rules as Barker wrote them. I make no claim that this is what he intended when he did so. Nevertheless, the set-up has worked very well, preserving the sweet spot of character power well beyond what would be the case if constant character improvement were the order of the day. I am immensely happy with the way Empire of the Petal Throne's experience system works in practice, as are my players. I think it's evidence in favor of preserving OD&D's awarding of experience only for monsters and treasure.