Hmm... honestly... it's not a bad idea.
The map will be my map for the first release of my mod. The mod will be developed for Source. We're starting with multiplayer, and depending on how things go, then create a single player experience. I could write an entire post about it, hehehe... but that's not really what this post is for. I just realized I didn't have a link to it in my profile. So I added one if you're interested in reading about it. It's a sequel to a mod for HL called Existence. Anyways back to subject...
Within the construct of the game... It *could* be possible to have a message display with a voice over radioing in saying something like... "What are you doing!? Get back to the target area!" Or something... It's still kinda evil... but I in certain ways it's no less evil than making some stupid obstruction that doesn't make any real sense. Then as you mention, you can really have the map go on as far as the eye can see theoretically. It's something kind of obvious that I seem to have overlooked. Again though, what do others think about that kind of warning? I guess it kind of depends on the context of the usage and how it's presented. In the worst case scenario it feels out of place, breaks the reality of the game, and basicly says, "Bad player! No!" If it works within the style of the game and doesn't look like a Fatal Error message I could see it being a feasible solution... even in combination with the 'logical obstructions' mentioned. In that way even if the player does circumvent the conceptual barrier you still have the message telling them to go back with the push barrier. That way you don't have any silly clip brushes keeping the player from jumping over obsticals and solves the verticle and horizontal dilema. Again though, so far it sounds like the best solution but I think you could make a solid arguement against it for the "Bad Player!" reasons. People could find that much more rediculous than simply preventing them from doing so. I guess it depends on the attitude of the player... which is one of those varaibles that's pretty unpredicatable in a lot of cases. Particularly with FPS titles as they have alot of applications and broad appeal for people who might enjoy completely different titles in other reguards.
-Dranore