Not really. It's less buggy when fully patched, but the worst bug you'll even come across no matter what is a bug that is a result of the engine or something. If you don't save really, really often, the game will crash more often. I save at least every five minutes in games that let me, anyways, so it's not a big deal for me.
Arx Fatalis and stuff like Ultima Underworld require absolutely no internet connection. Same goes for Shin Megami Tensei Strange Journey on the DS. If you do not have access to a DS, I can't say that last suggestion will be of much help. It just didn't have online anything, anyway.
The first two TES games are good offline games, but not sure if you have DOSbox on that computer. If you do, then go and try them out. If you have a computer that is connected, maybe you can just put DOSbox on a flash drive and import it into your non-connected computer. Ultima Underworld is surprisingly cheap on the PC if you get it off Amazon, but you may want to have DOSbox on your computer before getting it just in case.
Devil Summoner Soul Hackers on the 3DS requires no internet connection, but it's a 3DS game. I don't think you were wanting games on handhelds or consoles to be mentioned. If you have a 3DS, try tracking that game down. Might be a bit tougher to find now due to it not having gotten as much attention as Shin Megami Tensei IV did. The game's a port of an old Sega Saturn game that never got out of Japan until 2013 when it got a 3DS port.
I think Mount & Blade(the first one before Warband came out) can be installed and played without an internet connection, but I can't find any information that says it can. I even checked my copy of it and all this game has in the box is a disk and some cardboard.
http://forums.taleworlds.com/index.php?topic=53541.0
There's a ton of these types of games from the 80's and early 90's, but most of them will require DOSbox, so you'll need to use the internet to play a game that doesn't require internet before playing said game... What a strange situation. Not mocking you, this is just something I find interesting when I noticed a lot of what you're looking for would require use of a flash drive to get the correct programs into the correct computer.