How do people feel about modern/modernish settings?

[Quertus]

modern games need to be far more open and sandboxy, because players will notice the invisible walls far more easily. They might accept the castle wall being fireball proof, but you won't be able to reasonably stop them from blowing up a wall if they have acquired or somehow made decent modern explosives, for example. I think this might be why quertus feels modern games are more rail-roady, because in a fantasy game a small amount if railriading us easily hidden, but that doesn't go for a real-world setting.

That might be part of it. Thinking about it, I suspect that another part is where the game play occurs. In D&D, it largely occurs in "the rules". In a modern setting, it largely occurs outside the rules. If I've, say, done something IRL, but the GM is clueless, and doesn't believe it's possible, well, stupidity happens.

I may not be able to say, "but IRL I've melted this kind of rock with my fireballs", but I can dang well say... Hmmm... actually, maybe I shouldn't admit to just what all I can dang well say from experience.

But, yeah, that certainly makes rails far more visible, even if they masquerade as epic stupidity.