Those of you who played TW2000 1e probably not so fondly remember the abortion of a game that GDW put out called TRAVELLER 2300 (in 1e your characters had a 50:50 chance of starting the game either with 1 Hit Point or 0 Hit Points [aka DEAD] thanks to stellar proof reading!) ...
For those that managed to avoid that particular disaster, you may be familiar with 2300 AD, 2e or 3e.
Why is this relevant?
Well, I cannot recall for 2e (and I don't have 3e) but for 1e the plainly stated position in material available from GDW at the time (can't remember whether it was in their magazine or in the game itself) was that T2300 was the future of TW2000.
Yes, this was after the fact, but gives an idea of the line of thinking the GDW staff had as regarding the consequences of the Twilight War.
From memory (and I know someone will correct me if I am wrong), but recovery was assumed to be relatively quick in a technological sense.
This is, of course, completely at odds with the description of Poland in all editions and is hinted at by the stories of the survivors of the 5th Mech Division in all editions, who are based in Poland.
So, yes, Poland is something resembling a howling wilderness, as its been fought over for 5 years or so and heavily hit by Strategic AND Battlefield Nukes ... and that's the experience of the POV characters as well.
The rest of the world? The rest of Europe, even?
Given the supposed bad comms, assume the 5th Division guys really don't have a clew.
So, what is the rest of Europe like? Many areas will have been badly hit, mostly with Strategic nukes to major military targets. But the further away from the front lines the less likely they are to have been hit by Battlefield nukes ... and the more likely actual governments are to have survived in some form or another, and the more likely something resembling a function (if badly crippled) economy beyond subsistence farming is to exist.
Something similar applies to the CONUS and Canada outside of the immediate major target zones.
As for Central and South America and most of Africa, it's unlikely many of those countries will suffer any direct attacks (except those with major oil facilities ... and them only those facilities) and, yes, the disruption of international trade and of oil supplies will cripple their economies but won't actually destroy the infrastructure.
Lots of Asia will be the same (well, not Japan, the Koreas, Taiwan, and probably not China and Vietnam) with their economies crippled but not actually destroyed.
And how much do the grunts of the 5th Mech Division know about all of this? Bugger all ... less than nothing, except, possibly, rumours.
So take a lot of the 'Mad Max Howling Wilderness' shtick that the game presents as being unrepresentative outside of Poland.
Author: Space Opera (FGU); Rigger Black Book #1 (FASA); Orbis Mundi 2, The Marketplace, Ithura & Porthaven, Fantasy Europe (PGD); Road to Armageddon & Supplements, Displaced, Audace ad Gloriam, Farm, Forge & Steam (PGD).