Is It OK?

[NichG]

Hey y'all! I have my own opinions on this, but I wanted to kinda poll the community: When, if ever, is it acceptable for a GM to nullify player choices to get to a result the GM wants?

Interested in hearing edge cases, core gaming philosophy, etc. If you can spell out as many assumptions as possible that you're making, that would be appreciated!

I guess as a fairly easy example, when the choice is an implicitly available one (rather than a given one) that violates a previous agreement the player has made with the table. E.g. if you have a table rule 'no PvP' which everyone agrees to in order to participate in the campaign and then later one player says 'I have my character X sneak up while Y's character is sleeping and kill them in their sleep', then yes that was a player choice, but its not one you explicitly made available or baited them into and its one they previously had agreed to not take.

Another example would be when the unexpressed meta consequences of that choice would be relevant to table-level agreements but only due to information not held by the player. So in this case, the table pre-agreed to things about what they wanted out of the campaign - 'we don't want TPKs no matter what' for example. A player says 'I'm going to just shove all the treasure in this room into my portable hole'. The GM happens to know that the treasure contains a bag of holding, but the players don't. So the GM stops the action and says 'okay, if you take that action, its almost certainly going to be a TPK, and we agreed to not have those - before you manage to sweep everything in, you stop and notice a particular bag that seems a bit bigger on the inside...' Depending on the strictness of the table-level rules, the player may not be permitted to continue their original action (but then this reduces to the first sort of example).

If we're not talking about pre-agreement sorts of scenarios, then I'd say outright 'no you can't do that' or 'no, you don't do that' isn't acceptable, but there are adjacent methods which would be acceptable. 'Are you sure you want to do that?' or 'I want to ask the group if they're okay with that' or 'You can do that, but if you do I'm not willing to run the scene' or even 'If you do that, I don't think I have a way to continue the campaign, so as long as we're all okay with that being the last action in the campaign, go ahead...' Effectively 'I'm not willing to continue running the game if your character does that' is the same as 'you don't do that' in outcome, but it does so in a way that respects the player's agency more than just seizing control or directly negating something the player says. That doesn't make it a reasonable call to make in response to any little thing, but at least it leads to a discussion and future agreements on acceptable behavior rather than just a 'yes I do, no you don't' kind of fight.