Pool of Remonstrance

As I play through the well-loved 1988 AD&D computer game, Pool of Radiance (which launched the very successful "gold box" line of games), on the Wandering DM channel late nights Thursdays -- I'm reminded of the hard fact, for computer game developers, of how many ambiguities in classic D&D the programmers need to hammer down judgements for and back-fill in to complete the software. And this in turn leads to many surprises in store for the player who's become used to particular table rulings with their friends. I'm sure there's a similar phenomenon when players move between different human play groups. That's somewhat ironic, as AD&D was partly held out as a unifying solution to exactly those problems.

I'm still in the early phases of Pool of Radiance, but here's a small sampling of things that have jumped out at me as a surprise, many cases of which I've needed viewers to helpfully point out the novel ruling before I got in too much trouble. Keep in mind this is even while the designers and programmers have in very many cases been huge sticklers for hewing to the 1E books as written:

• Initiative is in a different order for each party, and intermingled between parties, on every round; i.e., it seems to have an individual initiative mechanic. (To me the 1E DMG seems clear that party-based initiative is in order.)
• Attacks against the back are determined not by position but by number of attackers -- one or two count as front attacks; the third or more attackers, or thief across from an ally, count as rear attacks. (This somewhat conjures the 3E flanking rule, abstracting where the "back" is on a figure. The 1E DMG kind of wants it both ways, arguing in some places for fully abstracted randomized-opponent melee dustups, and in others very exacting charts for the angle of flank or rear attacks. A chronic problem in D&D.)
• When in melee, you can actually run circles all the way around an opponent without triggering free attacks -- the free attacks only occur when you step fully out of contact. (Which is a legitimately narrow reading of the DMG language, but perhaps doesn't make sense in the spirit of the tactical game.)
• You can exchange items in hand -- weapons, shields, scrolls, etc. -- freely within any round. (This seems to butt up against the examples of rummaging in a pack or exchanging weapons in a fight; see 1E DMG p. 71.) Likewise you can thoughtfully look at all your gear and select any number of items to drop at your leisure within a fight (counter to the harrowing tale of Dimwall & Drudge in DMG Appendix O). 
• Diagonal moves on the grid are measured 1-2-1-2, etc., spaces. (There's no whisper of this rule in 1E; prior to playing Pool of Radiance, I thought that was a 3E novelty.)
  
• There's a "guarding" action option, in which you give up your action, but get a free attack if any enemy thereafter comes in contact with you. Likewise one can "delay" and wait for others to go first in a round. (Again, these are mechanics I associate with later editions.)
• One can cast spells freely in melee contact, except if you've taken any damage previously within the same round. (This is sort of the reverse of the DMG rule on p. 65 which dictates advance declaration of spells, before rolling for initiative, and then the results of that initiative possibly allowing interrupting attacks. Like Pool of Radiance, I actually do prefer not dealing with advance-casting; but I wouldn't want to track who took damage at what point in a round.)
• On the other hand, no missile attacks can be when one is adjacent to any enemy. (Which is quite sensible, but not in the books, and easy to confuse with the spell-casting rule which cuts the opposite way. You can't even shoot a missile if you're next to a sleeping enemy!)
• Having had to painstakingly fight the trolls on the 1st level of the dungeon, I'm still not sure if fire is needed only as the final blow, or at some point in the combat, or what, to prevent regeneration. Also: preventing troll regeneration by standing on the body is not a ruling I think any DM would come up with (although maybe necessary here just for the issue of not having multiple figures active in one space). Also: having a downed troll get back up with full hit points was a real shock to me! (But: It seems basically in tone with Poul Anderson's original regenerating troll encounter, and I actually plan to have trolls play possum like that until fully healed in my future games -- watch out.) And of course trolls breaking morale, so critical to that fight in the Pool of Radiance slums, is exactly opposite to where they're labeled as "fearless" in classic D&D texts.
• Also there's flaming oil which can be freely thrown, but there's no splash damage from misses (per the DMG). 
• Training to advance a level costs a fixed 1,000 gp (as opposed to the greater expense by level in the DMG; a saving grace in Pool of Radiance).
• The "option" the let characters go below zero hit points and possibly be resuscitated is in use (making combat much more survivable that if it was not). But the DMG dictate that a week's rest is then required is not used (although healing a downed PC in a fight does not let them get active again within that encounter). 
• Casting hold person allows you to individually select the multiple targets (whereas Gygax said more than once that spells of that nature would affect random targets). 

I could go on. None of these are bad rulings -- it's just that it provides a neat opportunity to re-experience the game as a "new" player at a fresh DM's table, in some sense, and think about all the ways I get to be surprised and think about different legitimate ways of running classic D&D.

Of course -- the thing that grabs my attention the most sometimes is 1E's very wonky relationship with scaling of distance and time. Pool of Radiance almost manages to hand-wave that away, but not quite. AD&D "inches" of scale directly convert to "squares" in Pool of Radiance for movement and missile fire. Many spells follow the PHB ranges and areas, but others were significantly modified. For example, the sleep spell in 1E PHB has a range of 3" + 1"/level, but I've discovered that in Pool of Radiance (without any ranges being listed in the game manual), the range is 3" + 4"/level. That's a big difference, and would probably have changed a few fights if I knew my Nirjarini, my 3rd-level magic-user, could cast it 15 squares, instead of the 6 that I expected.

Furthermore: Simon Wood on YouTube helpfully pointed out that the Pool of Radiance Clue Book (which I'd been avoiding) has a Spell Parameters Chart on its last page. I observe that the range given for every spell there exactly matches what's listed in the 1E PHB (except in two cases of 0-range spells, the area is swapped in instead: i.e., prayer and friends). So now I wonder: Are there other spells than sleep that are secretly off-book? Was the Clue Book author working directly from the 1E PHB and not the game, or an earlier design document? Is the sleep spell range change a conscious design decision, or an outright programming error? (Note that 4 is directly above 1 on a numeric keypad.)

Finally, exactly how big is a battlemap square in Pool of Radiance? Consider the following. A one-square wide corridor in the strategic view converts to four-squares wide in the tactical view (i.e., 4 characters standing abreast). So how big is that corridor, really? If we think it's 10' wide (standard for 1E dungeons), then the tactical squares are 2.5 feet wide. Or if we say the corridors are 20' wide, then the tactical squares are a 5 feet each (in line with later edition sensibilities). But neither of those options are present in the 1E core rules. Of course, the 1E PHB states that all indoor ranges and areas are a scale of 1" = 10 feet, whereas the DMG says that 10 feet will be represented by 3 actual inches on the tabletop (i.e., 1 inch = 3⅓ feet). So everything's up in the air with that math, as usual.

Party in a 1-square corridor in Pool of Radiance strategic view.

Party fighting NPCs in that corridor, with both sides packed 4 characters across.

I think the Pool of Radiance manual almost managed to expunge any reference to "feet" distance, except oddly for two spells interacting with invisibility -- detect invisibility and invisibility, 10' radius both have their area of effect stated in terms of feet, not squares. (I mean: obviously it's embedded in the name of that latter spell. But for the former, the 1E PHB & POR Clue Book give the range as 1"/level, while the manual says 20 feet per level instead, so that seems like a conscious addition by the video game designers, and another thing not reflected in the Clue Book?) So when I get higher level I kind of want to prioritize acquiring invisibility, 10' radius so I can test how many squares its 10-foot radius area encompasses. Maybe someone's already done that?

Edit: I got to use silence, 15' radius as a test case, and found that it has a radius of 1 square in each direction around its target. So that suggests each space is intended to represent 10' -- which matches a lot of the 1E book rules, but contradicts the rule that one can fit 3 figures across a ten-foot span (1E DMG p. 10). It also means that the "standard" corridors, as shown above, must nominally be 40' wide. As I've often said, the inconsistency and weird scaling of 1E rules always make something unsatisfiable like that.