To preface, I was thinking more about why each horn was worth entertaining, than trying to resolve them. Generally speaking -- per my general conclusion -- it's true that the features of each mode of TTRPG "risk" degenerate outcomes.
Grasping the first horn then, inadequate prompting is a problem found in some modes of play. I haven't observed it in sandbox, but I have observed it in Deathmatch Island. The game expects players to move node-to-node and engage the challenges they reach. In Phase Two they must engage with the Scout, Scramble, Battle Royale structures which have specific rules and sub-structures. If Production (GM) inadequately prompts the play can wind up eddying.
In sandbox, inadequate prompting is possibly masked by the result that players simply go in another direction. Seeing as GM had no particular direction in mind, it's never noticed that they inadequately prompted.
Again, I refer you to the example that I was explicitly given by others who favored an old-school sandbox experience: the "you didn't talk to the one-eyed [or one-armed, or various other maimings] man, so you never heard that the slimes in the mines are weak to lightning but
divide when struck by regular weapons, which means your death at their hands/pseudopods is entirely on your head." That's not an exact quote, of course, but it covers the core points: (1) the players were just supposed to
know that some NPCs in the tavern were necessary sources of information; (2) failure to interact with the one and only source of that information is construed as the players' mistake; and (3) any deaths/losses that result from failure to interact with that source are thus
earned by having made that mistake.
This isn't just a hypothetical. I
genuinely would have been caught by surprise by such a thing, in a game self-professed to be a sandbox, which would have gone completely beneath my notice if it weren't for these GMs (more than one!) explicitly saying that this is supposed to be an obvious prompt. Inadequate prompting, and resulting problems, were one of the earliest things I ever encountered when discussing this style with its own proponents, on this forum specifically.
I have been told, over and over, that the sandbox GM must not manipulate the players' choices. But in the very act of giving detail to thing X and not giving much detail to thing Y,
that can manipulate player choices. "Oh, this is the thing the GM wrote a lot about, it must be Important" is a perfectly natural thought for many players, of any style. Likewise, things that don't get any description at all are at risk of being written off as unimportant or non-interactable.
This is...kind of essential to the trilemma. The first path, giving no bias by (almost) never prompting, only waiting for players to act--but then the (from my perspective) very high risk of players never even considering something due to lack of prompting. The second, accidentally manipulating player action toward the things you prepared and away from their own choices/creativity. And then the third, overwhelming (or distracting) them with too much information by preparing lots about TONS of things so they won't feel pressured toward any given thing. Both extremes have (what seems to me) a high risk of not just undesirable but actively
harmful outcomes if the goal is heightened player agency; yet the seeming middle-ground risks a
different threat to player agency.
Really? I can't imagine why. If it's easy to see why a dearth of information would be a possible problem, why would overcorrection, flooding the player with so much info they can't keep track of it all, or so many options they break down into analysis paralysis, not be also reasonably easy to grok?
What do you mean by "incorrectly" induces player action? What would be an incorrect player action in a sandbox?
I already clarified that in the post itself, but you have misread what I said. I wasn't saying the
action was incorrect. I was saying the
inducement is incorrect. The idea is that there are some ways to induce which are good, and other ways to induce which are not just bad, but
extremely bad, as in, outright contradicting the purpose of sandbox play.
The player actions themselves were never even under consideration.