What now? It's unplayable if they DO respawn or a disgrace if they CAN'T?

Yes, they usally do respawn ([url=http://en.uesp.net/wiki/Skyrim:Respawning]Skyrim: Respawning[/url]).
However, there are places that never will ([url=http://en.uesp.net/wiki/Category:Skyrim-Places-Safe]Skyrim-Places-Safe[/url]). Those are places you visit while on specific quests (or personal homes) and therefor tied to happenings during the quest.

The console versions are the same as PC vanilla without mods - there's no difference between them.

I think one of the job requirements at gog is to play as many game as you can, no matter the platform ;)

Touché.

Strange question: Is it possible to kill all enemies in the entire game before any of them respawn?

No.

Why not?

Have you played it? I suppose it could be done with ''God mode'' cheat.

I haven't played it, but if it could be done with cheats, it could probably be done with Fortify Restoration potion abuse. In any case, just because it looks impossible to do something in a game doesn't mean it is.

Remember, people have beaten (for some definition of "beaten") Super Mario World without leaving the first dungeon and Zelda: A Link to the Past without first reaching the Sanctuary.

Also, don't give me a "this game has no bugs" argument; we all know that Bethesda games are full of them, and some of them are definitely exploitable.

I think it is not possible due the the size of the map. If mobs redrawn in 10 days, you can not manage to go from corner to the other in that amount of in game time.then add a day or so for each dungeon you are clearing.

I seriously doubt it, the world is too big for that.
By the time you got to the other end several in-game days would've passed resetting the cells you did first.
And that's just for the overworld, there'd still be tons of dungeons to do.
And Dragonborn adds a new island.
So without cheating, I'm fairly confident the answer is no.

I would not believe it possible at all without using cheats.Don't believe I mentioned bugs.

Yes animals and enemies respawn in various areas by design. Not only is the game completely playable, but millions of people have played it, and multitudes of people have finished the game, so it is indeed playable.

The bigger problem is the tens of trillions of bugs in the game, many of which are game breaking that you may encounter which can totally screw your game over until you search Google and find other people experiencing the problem out there and read up potential solutions and workarounds for the given problem. Fortunately enough though there are many great Skyrim resources online for working around the bazillions of endless bugs in the game. Several Skyrim wikis out there have a section at the bottom of each of their pages for "Bugs" and if/how to get around them, often by going into the game's console and typing commands. There is also an unofficial patch for the game made by the community and available in the Steam workshop as a mod which fixes hundreds if not thousands of bugs in the game although I haven't tried it out yet personally but a lot of people swear by it.

So respawning enemies definitely do not make the game unplayable, however unless one is willing to use the unofficial game patch or be comfortable with googling around for workarounds to the endless bugs in the game, then one might consider it unplayable due to hitting a game breaking bug or one that might not break the game but makes it very unsatisfying and immersion breaking and frustrating. IMHO though if one is patient enough to play all the way through a 200+ hour game, as unacceptable as it is to have to surf the net for hours to find bug workarounds and deploy them, it is minor amount a of time compared to the fun time in the game. :)

Dunno about that. I played 150+ hours vanilia on this game, and although there were some bugs, there was nothing that I would call "game breaking". Some pretty weird stuff (like the way my wife fled the chapel just after our wedding), but nothing serious enough to pull me from the game.

I got bored before I finished the main quest, though. Maybe the worse offenders are in the endgame? Or maybe I just got lucky.