The Monster Kills XP Economy

Advancement systems in D&D must always, to my eye, be intrinsic, pseudo-objective and at least quasi-quantifiable. They should in other words relate to events that happen 'in universe' rather than in the context within which play take place (ruling out, for example, XP for 'good role playing'); they should leave as little as possible to subjective judgments by the DM (ruling out, for example, 'story goals'), and there should be some plausible connection between the amount of XP awarded and what it is being awarded for (1 XP per GP; 25 XP per HD of monsters killed; etc.). This is all geared basically towards keeping the DM somewhat honest, and ensuring that the incentives point towards player agency rather than railroads - the result should be that the players want their PCs to go on adventures because of some intrinsic motivation rather than 'because it's the plot'. If the PCs are getting XP for 'story goals', they are by definition wedded to 'the story'. If they get XP for treasure, all they have to do is look for treasure - wherever and however they like.

(I say 'pseudo-objective', because in the end the DM is in charge of setting up the conditions in which play will take place, and it is therefore always inevitably within his gift to determine, for example, how much treasure is actually available in the setting for the PCs to discover, what monsters inhabit the local region, and so on and so forth. And I say 'quasi-quantifiable', because obviously to a certain extent the relationship between the XP value and the underlying token - GP, say, or monster kills - is arbitrary; why should it be 1 XP per GP rather than 1 XP per SP or 5 XP per GP?)

All of this is now known and I know that I am teaching all of you grandmothers out there to suck eggs and preaching basic, primary school level OSR knowledge. But still, it seems important to lay out my bona fides all the same.

XP for gold is therefore in any case the gold standard (see what I did there?) for an advancement system, because it does exactly what it says on the tin - it provides an incentive for the PCs to adventure and it prevents DM arbitrariness. But there are viable alternatives. One would be XP for exploration - based on the number of hexes travelled, or the number of hexes fully explored, or a similar mechanism. Or one could even come up with a method for awarding XP for 'adventure' - giving XP for simply encountering things, or being made subject to particular magical effects, or for descending dungeon levels, and so forth.

The main rival for XP for gold, though, would probably have to be XP for monster kills, since it seems to make intuitive sense: combat is after all often the most enjoyable and immersive aspect of play, and it has an 'in-universe' logic to it in that killing monsters is probably both useful and would also help a person develop his abilities in the crucible of life-and-death confrontation. 

When I run D&D I mainly rely on an XP for gold system but I do award XP for monster kills on the basis of the little table found in the Rules Cyclopedia. What this typically means in practice, though, is that XP for monster kills is like a thin sliver of icing on a very fat slice of cake. It is big treasure hauls which see PCs advancing from level to level; the monster kills don't really move the dial. What I don't see emerging, in other words - because the totals are so comparatively small - is a monster kills XP economy. 

What I would expect if I increased the XP awards for monster kills (from, say 25 XP or so per HD to 250 XP) and abandoned XP for gold entirely is a radical restructuring of player incentives that I think would play out as follows:

• Players would still be incentivised to go out on adventures but their tolerance for risk would I think increase. Under an XP for gold system, the incentive is to try to amass as much treasure as possible while minimising the risk of monster encounters. An XP for monster kills system would I think reward more risk-taking behaviour: trying to take out the local ancient red dragon despite perhaps not quite being 'ready' for it, because of the big XP haul that would result.
• A genuine monsters kills economy would I think emerge, in the sense that the players would still need to get money from somewhere to fund their lifestyles and buy their necessaries. It seems likely that the selling of monster body parts would become quite an important aspect of what would happen during gaming sessions; it also seems likely that securing payment for bringing in bounties or monster scalps - or even assisting in trophy hunts - would also become part of proceedings.
• Aimless roaming might be encouraged. PCs would actually desire, rather than actively avoid, random encounters. And they may very well decide that simply striking out into the wilderness on long journeys would be a good way of triggering them.
• Killing monsters would become more important than defeating, out-smarting, or avoiding them (without, of course, a tweak to the concept). This would result in a more violent and aggressive approach to the game world - although this might be channelled in an interesting direction if XP was only awarded for killing certain types of monsters (demons or evil undead, say, in a game in which the PCs are all paladins). 

This seems to suggest that the result would be a more 'gamified' and superficial engagement with the setting on the part of the PCs. Discuss.