Is that spectrum based on time/date line or a set of aspects?
1978 - most old school
1980 - moderately old school
1985 - least old school
or
Plot-less, ecology-less, monster-filled dungeon crawl - most old school
Minor plot concept, some sense to monster placements, dungeon - moderately old school
Fully detailed plot, logical monster placement, not a dungeon - least old school
?
Well, as with so many labels (whether old or new school), there's more to it than a simple linear relationship between release year and plotness; I'm not at all sure that's exactly your intent in the structure you created above, but it seems at least implied. In any event, to address that: in my page counts post I removed the stats I'd done on some JG products, including Caverns of Thracia and Dark Tower (both by Paul Jaquays) since this thread has been just about TSR stuff. But, they're relevant here: DT and CoT were released in 1979 and were the longest modules published that year, as well as to date, at 72 and 80 pages respectively. Both were also very ecologically-minded dungeon designs, with various sub-plots you could explore, cultures to interact with, and NPCs to chat up. They clearly show that Paul Jaquays was ahead of his time by at least 5-7 years, and that even "core old school values" modules can still address the more rounded, story-friendly approach without becoming the DragonLance plot train.
These dungeons were all pretty much linear to the McGuffin(s):
White Plume Mountain (92%)
Tomb of Horrors (98%)
Hidden Shrine of Tomoachan (76%)
Ghost Tower of Inverness (78%)
But these had more meandering labrynths:
Pharoah (28%)
Ravenloft (30%)
Beyond the Crystal Cave (25%)
How much "old school weight" does less restrictive map design have?
Melan's mapping analysis thread @
http://www.enworld.org/forum/genera...n-layout-map-flow-old-school-game-design.html (which Philotomy also linked to) and the semi-related Castle Greyhawk maps thread @
http://www.enworld.org/forum/genera...ld-these-maps-make-fun-dungeon-adventure.html speak to the openness of the map designs. I haven't sat down to do the analysis in earnest, but my hunches on how these would play out follow (perhaps we can entice Melan to pull out his Visio templates again?!

):
- S2 should be rather like a trident/three-pronged fork, in structure, with some loops and spokes here and there (like a three-caves Caves of Chaos).
- Similarly, the loop structures in the first tier of C1 make me think that it would look most like level 1 of B1; the rest of the tiers are pretty linear, though, because they're so small in area
- C2 is fairly linear in tourney play (choose a tower entrance, find the center, ascend through the tower), but in campaign play I think folks would be more inclined to explore the other paths from the other towers, too, which starts to introduce loops into the flow; or, perhaps it's just one loop, with multiple entry points (like the arms of a whirlpool); hmmm; Melan?

- The fact that the "big" encounter at S1 occurs that the end of the module doesn't in fact mean that the map design itself is linear. In particular, S1's use of the false entrances, teleporters throughout, the various "segments" of the dungeon, the use of one-way doors suggest to me a design that's more like an amalgamation of B2 and G2 from a flow-chart standpoint.
- I don't have copies of UK1 or I3 handy to check, but my recollection of I6's map design (of the castle) is that it's a pretty open design, and that it would be very complex to map out into a flowchart, especially given the verticality throughout the levels. So, in that sense I think it's a very open map design. That doesn't preclude the module from being more story driven/new school in approach either, though. I think I6 occupies an in-between place between the old school designs, with the Dragonlance-like plot determinism, without quite falling into either side cleanly. The plot elements of I6 allow for a lot of determinism (the gypsy fortune decks determining the location of items, what things have to occur to kill the Count, etc.), but they're also random in nature; the map for the Castle is very open, but the lands around Ravenloft itself are bounded by the mists that prevent reaching outward (which is rather demi-plane-ish!).
But, as the comments to Blondie earlier speak, map design is not the only litmus test by which an old-school dungeon is created---and nor should it be! In addition to a more-open map design (in general), I think the following criteria also fit somewhere in the mix:
- stuff that's out of bounds/beyond mortal ken and PC understanding, but is just too cool not to want to explore/steal/fight/etc. (Kuntz's Unopenable Doors and Terrible Iron Golem in WG5 are great examples of this)
- lots of options/paths for player choice/exploration, both within the existing level and up/down to other levels (the latter is most applicable to a classic mega-dungeon environment vs. to a published module, though)
- challenges for the players as well as the characters (riddles, puzzles, logic tests, mapping, resource management, perhaps a looming deadline, etc.)
- introduction of new monsters, spells, treasures, etc.: you and your PCs haven't seen everything under the sun yet (this could be a subset of the above point, too)
- lightweight background to make the scenario more easily adaptable into a homebrew campaign (the A-series is probably as dense as the background should be, in my book)
- the dungeon environment is part of the challenge, and takes the players out of their "comfort zones" (S1 is the classic example, but S3 and Kuntz's Maze of Zayene #1-2 are great example of this, as is A4's dungeon---if the PCs fail to escape they die in the collapsing dungeon!; teleporters and passages to other dimensions also fit in quite nicely here)
- lots of room to expand further, with hints to spur on the DM's creativity: Gary's dungeons were rife with places where the enterprising DM could insert rooms into an existing level (G1 dungeon level) all the way through entire new levels demanding to be detailed (D1 and S4 are probably the best examples of this)
- many hidden treasures in out of the way nooks, hidden encounters, hidden sub-levels, etc. that the players will have to be smart to be able to find in the first place, and then be smarter to overcome (WG4's Black Cyst is a great example of this; none of the players I've ever run through this have found it without me providing too many DM hints to them to steer them toward it)
I'm sure others will come up with further examples, but those are some core traits that define old-school adventures for me.
list of magic "that doesn't work" - While "old school" play generally encourages and rewards creative use of magic, there is an undercurrent that "bans" certain magical effects from operation to stop certain "shortcuts" in some circumstances. This stems from the general emphasis on player ingenuity as the engine of success rather than mere character ability (i.e. using certain magical effects as "trumps").
I think that this also fits nicely with taking the players out of their comfort zones idea, too: they have to rely on other tools vs. their standard toolkit (whether that toolkit is divination magic or teleport/dimension door for a quick escape or whatever).
exploration of wilderness "hex-by-hex" - "Old school" play is most associated with "dungeon crawl" game-play;
Ironically, there are few good examples of wilderness crawls in TSR's AD&D works: S4/WG4, WG6, and L1 are really the only ones in the pre-1986 modules (perhaps N5 Under Illefarn too?---it's been awhile since I read that one). Many modules strongly hint at the DM adding wilderness explorations before the PCs arrive at the dungeon (A2, G1-3, I1, S1, T1's environs, etc.), but few provide good models for wilderness exploration. The X modules have a few more, I suppose (X4/X5 being an excellent example), but I haven't reread them in years and years, and never owned most of the later X modules.
In the designer notes, Gary remarks that the original players from the Greyhawk Campaign (Ernie Gygax, Rob Kuntz, and others) that found themselves in the Isle of the Ape fled as soon as they were able; no group of players ever "completed" the adventure. "Running away" in the face of seeming overwhelming adversity is very "old school," in my opinion. There is no presumed assumption of character survival or balanced encounters.
Another excellent point!
