I've written about the statistics of OD&D treasure placement a few times in the past. For example, here's short an assessment of the Vol-3 dungeon treasure tables, and here's a longer analysis of treasure types and XP awards in OD&D, Holmes, Moldvay, etc.
One of the primary observations from that latter essay is that, by the book in OD&D, the famous monster "Treasure Types" don't really get used in dungeon play. The monster numbers appearing are really intended for high-level wilderness gaming (with humanoids teeming in the hundreds per encounter; this point is reiterated in many sources), and since the treasure types are proportional to those huge numbers, they are not really suitable for dungeon play, either. The OD&D Vol-3 "Distribution of Monsters and Treasure" makes this clear:
It is a good idea to thoughtfully place several of the most important treasures... and then switch to a random determination for the balance of the level... To determine the kind of treasure use the following table... [OD&D Vol-3, p. 6-7]Note that the "following table" is not the treasure type letter-table, and that by the book this new table is used for treasure both with and without monsters (as opposed to later editions, which tend to use a separate table solely for "unguarded treasure"). We might ask: why this disconnect? Well, to my eye in places the various OD&D books appear like sequential progressions, in some ways modifying the earlier volumes even in the same original boxed set. I suppose with fairly lightweight editing they might evolve that way while being written. Additionally, there are sources saying that the Vol-2 monster numbers and treasure types were the work of Arneson for his wilderness game, so it would also make sense for Gygax to create a distinct system for his dungeon play. Just a theory.
Anyway, two main conclusions from last time (thinking of the famous Moldvay observation that "most of the experience the characters will get will be from treasure (usually 3/4 or more)", in Moldvay Basic p. B45): (1) the 3/4 (75%) of XP from treasure only works with the treasure type tables if we discard the In-Lair % check from OD&D, as Moldvay indeed does; and (2) the amount of XP from treasure by the dungeon tables is actually on average less than the monster XP, so in my house-rules I was set to multiply XP by some factor to make up for that fact. While item (1) still seems solid, today I'm backtracking on (2) for a few reasons: first, I was only looking at an average of all monster types, not by level; and second, perhaps more importantly, for treasure purposes I'd made the "monster level" max out at 6, as per the Wandering charts -- and so the higher levels of treasure in Vol-3 were simply missing entirely.
Here's a new chart where I estimate the overall number of monsters, treasure, and XP for each level of a dungeon by the rules in Vol-3, with the standard interpolations where necessary (click to enlarge below; or choose PDF or ODS format):
Note here that I'm assuming an encounter at level N is with 1d6 monsters of hit dice N (with XP awards as per Sup-I). While the Vol-3 random monster tables are labelled "Monster Level Tables [1 to 6]", currently I'm thinking that it's better to interpret "monster level" as simply hit dice for a few reasons. One is that you have the example in Vol-1 of a troll being referred to as a "7th level monster, as it has over 6 hit dice" (p. 18), different from the wandering table that it appears on (5th). Second is the implication to increase monster numbers if dungeon level exceeds monster level (Vol-3, p. 11), which gets quickly ridiculous; anything past dungeon 6th level and you'll be multiplying the number of dragons, balrogs, hydras, etc. (max 6th level wandering chart) by some unknown geometric powers. Third is that "monster level" can then scale with hit dice, and XP are properly a function of monster level up to 21st (similarly: both the Vol-3 treasure and wandering tables max out at the same 13+ dungeon level, not just 6th). So that's basically the first column of numbers.
I found that the results of that new assumption were entirely fascinating when they popped out at me tonight. Here are some observations from the spreadsheet above:
- At low levels, the treasure:monster XP ratio is much higher than Moldvay's 3/4 figure (see 2nd column from the end): it's actually 95% at 1st level (i.e., a ratio of almost 20:1)! Then it gradually decreases to the level of about 75% around the 17th-20th levels of the dungeon. I might call this a nice "starting boost" to XP at the lowest levels. (This would be compatible with my prior analysis, if I had separated out the lower-level monsters and noticed how much higher their treasure:monster ratio was from the overall average.)
- A while back, I made a personal note to myself that I wanted the first level of a dungeon to level-up a party of five fighters, i.e., give 2,000×5 = 10,000 XP. Well, look at the first entry under "Grand Total XP": purely by coincidence, it's just a bit over 10,000 XP.
- More generally, look at the column "Party of 4 PCs: Fighter Level", which shows level gained by a modern party of 4 players if they all had fighters, after clearing out each indicated level. Basically, they get one character level for each dungeon level. For dungeon levels 1-6, they almost always end at level N+1; then there's a bit of a flat spot for PC levels 8-10; and then after dungeon level 12 they go on to gain exactly one level per dungeon step. (Of course, magic-users might be one level behind, and clerics/thieves one level ahead, due to their different XP requirements.)
- On that latter point, look in particular at the bottom-most entry under "Party of 4 PCs: XP Each" (per level): for levels 21+, that XP value is 123,003 -- almost exactly the 120,000 XP that fighters need to gain anything above "name level" in OD&D. There's no way this was pre-planned in OD&D (it's not even the same number of players they'd use then), but I found this almost unnervingly synchronous.
- A different perspective is given by the "Party of 8 PCs", where I consider the approximately double-sized party used in the old days (in official modules and such). At low levels, the party might be one level behind the party of 4 PCs (which should be obvious, since half XP puts you one level behind in a geometrically increasing XP requirement situation). At the highest levels, once you get to the fixed XP increase per character level, then the party of 8 gets a bump every 2 dungeon levels (instead of every 1 for the party of 4).
- A critical point, as I've made before, is that commonly the vast majority of treasure and XP value comes solely from the jewelry component of the treasure (see the very last column of the chart). At the 1st level it's 77% of all XP; it remains the majority of all XP awards through the 10th dungeon level; and it only decreases to about 1/3 in the range of the 13th-20th dungeon levels (when treasure is fixed but conceivably monster XP keeps increasing, as per Sup-I).
- Interpretation of this key point on jewelry: In the 1st dungeon level, according to these parameters, we can expect exactly one treasure with jewelry. (50 rooms × 28% with treasure × 5% chance for jewelry = 0.7.) But this one treasure is worth around 12,000 gold on average (3,400 ×3.5 for 1d6 pieces = 11,900), which is practically all of the treasure value, and over 3/4 of all the XP for that level. If that one jewelry treasure is either missing or goes undiscovered by PCs, then their XP will be only 1/4 what it would be otherwise, and they will definitely lose their chance to level-up before delving deeper into the dungeon. (To the DM: if you roll a big jewelry treasure on the 1st level, then don't skip it for being too generous: it's expected that one of those is in there each dungeon level.)
- Or in other words: Exceedingly crafty players (especially thieves) might actually consider a strategy of foregoing the metal-coin treasure entirely, and focus solely on retrieving the gem-jewelry-magic treasure exclusively -- which while giving the majority of the treasure value, adds negligible encumbrance while moving and exploring.
A few caveats or assumptions that I should make clear (if they aren't already):
- I'm assuming that there are about 50 rooms or so per level, which is about what I get from a piece of 30×40 graph paper, if I make a fairly dense dungeon map. This should generate about 17 monster areas (1/3), and can be cleared out (and thus level up) in maybe 2-3 play sessions of 4 hours each (judging 2 sessions × 4 hours × 9/4 rate = 18 based on a small sample of prior play records). If you make smaller or larger dungeon levels then the per-level rates change.
- The number of monsters appearing is assumed to be 1d6 across all encounters; that is, an average of 3.5, approximately equal to the small party size. There is a lot of ambiguity in Vol-3, p. 11 regarding "Number of Wandering Monsters Appearing"; while that source says that larger parties should confront proportionally larger monster groups (not implemented in the chart above), no such statement is made for the treasures. Therefore, by the book, small parties benefit from finding full treasure without facing increased monster groups.
- Values in the chart assume that the entire level is liquidated; to the extent that any monsters are bypassed, or hidden treasures unplundered, then the totals shown will be decreased.
- The chart doesn't take into account PC casualties (lost XP), and/or how the DM implements any rule on replacement PCs.
- I didn't take into account the rule on pro-rating XP for high-level PCs versus low-level challenges (Vol-3, p. 18); as long as PCs adventure at or above their level (as occurs in the chart naturally) or close to it, then this effect will be negligible.
- Values do not take into account DM-placed "most important treasures" (as per the quote at the top, Vol-3 p. 6), which of course could completely outweigh anything else shown here. However, my recommendation would be that such crown-jewel treasures should be set at some level above the averages in the chart, and in point-of-fact, actually include real jewels.
Final Conclusion: If we use the dungeon treasure tables from Vol-3 as written (and ignore the lettered "treasure types" as for wilderness only), then the result is that small PC parties will generally gain a level for each dungeon level cleared, and there is no need to modify or multiply book XP awards in any way. However, care must be taken to include adequately large treasures, in particular caches of high-value jewelry, especially in the DM-placed "most important treasures" -- even starting at the 1st dungeon level.