There is an interesting discussion on Terminally Incoherent about invisible walls. Luke seems to feel that they kill immersion. Apparently, so do everyone else that commented on his blog.
Always the contrarian, I have to defend the opposite position: invisible walls enhance immersion.
One of the irritating things I find in many RPGs that have "open worlds" where you can interact with everything is that everything is so damn small. You walk into the mining village and there's like five people who live there and three houses. Obviously the game developers have limited time and it doesn't make sense to design the game world with realistically sized mining villages with hundreds of NPCs and fully interactive homes because it would take them forever to do just that and then there'd be no time to actually make the damn game. So I understand that. But they have a choice:
- put in fake backdrops of "the rest of the village" but make it so the player can't go there, OR
- make the world unrealistically small so the developers have time to implement every facet of the game world and therefore won't need to upset player's illusion of interactivity and control
I prefer the former. I find it curious that people insist on the latter. Last time I checked, few RPGs put bathrooms anywhere in game, and I can't remember the last one that made me use one. So obviously as consumers we all draw the line at how much immersion we require somewhere.
When you get to the edge of a map, the game developers could put in an invisible wall to demonstrate that the game world continues, OR they can go out of their way to put in all sorts of natural barriers so you simply can't continue. Again, I prefer the former. Wrapping the entire game world with barriers just exaggerates how unreal the game environment is and ruins the illusion. Who builds nations in the middle of impenetrable valleys that you can't get goods in and out of?
I prefer the game world to feel realistically consistent. And that means having the maps appear to continue even if they don't. After all, if your RPG consists of a map of a nation, they probably do trade with other nations. That's not very plausible if you can't get an individual outside the borders of the nation, let alone a caravan. With an invisible wall, you can see that the world goes on, but from a role-playing standpoint, your character just doesn't want to go there.
In other words, I prefer the illusion of a continuous world even if it means sacrificing the player's control at certain points.
I do think that perhaps games could implement the invisible walls better. Instead of having you continue to run in place once you hit the wall, as most do, just have the player stop running and say "I don't want/need to go there," and/or turn them around. That way you can maintain narrative immersion (that the world continues but your purpose is so important you can't go wandering off yet) without violating the immersion of control.
There's no right or wrong here. It's all a matter of opinion. In Grand Theft Auto the city is big, big, big. It's a city after all. That's narrative immersion. But because it's so big, obviously the developers can't make every indoor area. That means some doors can't be opened (they are simply fake backdrops). That violates the illusion of control, which for many makes the game less immersive. You now have a game world where you can kick down SOME doors but not others, arbitrarily.
So what do you prefer your games focus on? Narrative immersion (if they say it's a city, it should LOOK like a city), or illusion of control (if there's a door, I should be able to open it)?