While I'm perfectly fine with invisible borders, you can drudge up explanations for most of the methods mentioned above.
Maybe the blizzards are the result of Skyrim experiencing an extremely harsh winter. Maybe the borders are being locked by the Imperial Legion/other provincial forces in order to try and prevent civil dissenters from spreading.
The unclimbable mountains obviously wouldn't work, of course.
I really don't see the reason why invisible walls shouldn't be used though. The game is set in Skyrim. Its up there in the title. If you're trying to cross the border the whole "it breaks immersion" argument doesn't cut it, because you know when you buy the game that you can't travel all over Tamriel.
Maybe the blizzards are the result of Skyrim experiencing an extremely harsh winter. Maybe the borders are being locked by the Imperial Legion/other provincial forces in order to try and prevent civil dissenters from spreading.
The unclimbable mountains obviously wouldn't work, of course.
I really don't see the reason why invisible walls shouldn't be used though. The game is set in Skyrim. Its up there in the title. If you're trying to cross the border the whole "it breaks immersion" argument doesn't cut it, because you know when you buy the game that you can't travel all over Tamriel.
Well, you can come up with explanations if you try really hard, but to stop them having holes they just have to end up seeming a bit ridiculous. If Skyrim is experiencing really harsh weather, why do you only experience this exactly atthe edge of the province, and ALL THE TIME? If Skyrim is in civil war, a) Why would they put all their main energy into border patrol and B) What trouble to the Empires control over Skyrim could be better achieved outside of Skyrim than in?
An improvement to the current invisible wall system would be to have it so that you stop the running animation when up against it, so it doesn't look like an invisible wall and more like your character just doesn't want to go beyond that point.