It's not going to make it better for people who like creating or learning world lore.
Probably someone has mentioned but the rules for
Ironsworn are free. I've not played the game but when I did PbtA I had a similar experience to Hussar for a time...like, "wow, it's so easy to run games, so easy to improvise this system, I can get so much done".
That faded after a while because the lack of fixed content and challenges started to bother me. It felt less and less like a game and more like a storytelling aid. A bit too much anything goes.
After that phase I entered my "lots of structure is good, fixed worlds are good" era, where I am now.
The problem is there is lot of subjectivity about the topic it is "good" at. Is it easier to make a sandbox in Ironsworn than D&D? For me, no, because Ironsworn isn't creating something that I consider (for me) to be a sandbox. It's a storytelling game, it constructs an emergent narrative.
Ironsworn is no more a "storytelling game" for constructing "emergent narratives" than is classic D&D.
Both are games in which one participant - the GM - manages backstory, scene-framing and adjudication of resolution; and in which the other(s) - the player(s) - play(s) the game by declaring actions for a particular imagined person moving through the world and the situations that the GM is presenting to them. And in both games, the shared fiction matters to the resolution of those declared actions - this is what makes them both recognisable as (and straightforwardly recognisable as) RPGs.
The most obvious way in which they differ - especially in the context of this discussion, about sandboxing - can be seen by reference to their rules for resolving a journey:
The Ironwsworn rules were posted by me, upthread. To get started, they require a decision to be made about the degree of danger/challenge that the journeying characters face (is it troublesome, dangerous, formidable, extreme or epic?). Then, resolution can begin - that is, the dice can be rolled. Once the outcome is noted - either reaching a waypoint or paying the price - there needs to be narration of that. But that narration doesn't need to be known in advance of the rolling. This is what makes it possible to resolve the journey with little or no preparation. This is also what makes it easy for the GM to involve the players - for instance, asking the players to suggest a likely waypoint (eg "Your character is from these parts - what's the first major port of call when sailing down this river?") - because (i) you don't need these questions answered to resolve the action declaration, and (ii) the players don't get any particular advantage from answering one way rather than another. There's no "conflict of interest".
The classic D&D rules for resolving a journey are pretty well-known, I think. The GM refers to a prepared map (often, even typically, a hex map), and correlates the scale of the hexes with the movement rate of the PCs. The players tell the GM which direction their PCs are travelling in; a roll is made to see if the PCs become lost; and the GM then then plots the PCs' movement on the map. The GM uses two methods, concurrently, to determine what the PCs meet/experience: encounter rolls, which can be improv-ed similarly to Ironsworn; and reference to the map key, which records information about at least some of the hexes. That second bit is - at least canonically - prepared in advance, together with the preparation of the map itself. That advance preparation is what makes the GM's narration of events, especially advance events, non-arbitrary/hosing. And because the content of the map and key directly affects the players' chances of their PCs successfully completing their journey, there is a good reason not to ask the players for a lot of input as the journey is resolved - because the players do have a conflict of interest.
If, by "sandbox", is meant a game in which the GM has prepared that map and key in advance - so that the players are, as a central part of the play experience,
learning what the GM has authored about the setting - then classic D&D is clearly going to facilitate a sandbox. Whereas Ironsworn probably won't - it's journey rules
can be combined with a map and key, but that's not necessary and probably won't bring out the strongest features of the game. This seems to be what @TheFirebird has in mind in saying that they don't consider Ironsworn to be a sandbox game.
If, by "sandbox", is meant a game in which there are no limits (beyond genre, good taste, table agreements, and prior established fiction) on where the players can have their PCs journey and what those PCs might experience - which is what
@Hussar seemed to mean, not too far upthread (
post 2109 - "totally sandbox, total player freedom") - then Ironsworn seems to the better game. Because inherent to the resolution technique of classic D&D is that the GM has already decided some stuff, and this constrains and delimits what the players might have their PCs do.
And you can't have it both ways. If the players are going to learn pre-authored stuff, then that stuff has to be pre-authored; and the way they will learn it, in RPG play (as opposed to, say, just reading the GM's setting bible), is by experiencing the way the GM uses it to tell them what consequences flow form the players' action declarations for their PCs. In other words, of necessity that stuff imposes limits.
That's its point.
Conversely, if a game is being plaid in which there is "total player freedom" in Hussar's sense - ie the fiction about
where the PCs arrive and
what they experience is made up on the spot, perhaps by incorporating players' answers to questions - then, by definition, there is no pre-authored material for the players to learn. Rather, everyone at the table is learning, together and as an output of hte process of play, what their shared fictional seting is like.
To me, the contrast I've just set out - which begins with resolution techniques for journeys, and relates those to prep, and then to player experience - seems fairly straightforward. But no doubt some posters will disagree with it!