You cannot install a Steam game offline. It needs to connect to the Steam servers the very first time to confirm you own the game.
If you do not want to redownload the game, go online, click install, let it go as far as where it starts downloading, close Steam completely and copy the files from the SteamApps folder on another machine, then launch Steam again. However, this process still requires an internet connection on first play.
I know of only one way that this can happen in windows, and has nothing to do with Steam other than their not-so-great decision to install all content into Program Files.
If you are on Windows 7 or Windows Vista, and you have UAC set to ON, then change it later to OFF, this can happen.
UAC does thing evil thing where if a program tries to write to a "protected" area like Program Files, EVEN IF YOU ARE ADMINISTRATOR, when you get a UAC prompt and give permission, it actually writes any files that would normally go into that directory into a "virtualized" directory somewhere else.
If you turn off UAC, that will no longer happen, and as an awesome bonus, it will no longer know about the files that it virtualized.
So in your case, if you had UAC on, installed a ton of games, then later got sick of UAC and turned it off, this would happen as you described.
See the second paragraph in "Features" in the article on User Account Control.
If you have done this and turn on UAC again, your content will come back, but be a TOTAL mess because if you've downloaded more stuff with UAC off, then that will be invisible when you turn UAC on, and vice versa.
this drove me a little crazy once before I realized what was happening.
i'm curious to know if this is your issue.
Best Answer
The redistributables are quietly/silently installed using commandline switches/flags. This makes it slightly faster & less annoying as it doesn't have to show the installer window or wait for us to click through the installer.
With "SteamWorks Common Redistributables" (SCR) they are setup by devs, but the install scripts and redistributable installers themselves are managed by Valve. The devs can apparently still manage their own installscript.vdf to do this, but it'd be much easier to just opt-in to SCR.
The installers themselves seem to use whatever names they were given by Microsoft or whomever develops & licenses them to others, so if it's a web-based installer it should be obvious (if you can find it in the Steam folder). e.g. "dxwebsetup.exe" vs "directx_MonYear_redist.exe".
I can't check as my PC is dead, but there's no good reason for Valve to use web installers, and in my years of poking around I never saw a web installer for a redist in any of the few hundred games I installed.
That being said we do need to note that devs can include custom or uncommon redistributables that they will package with their game. So, yes it's still possible to have web-based installers from the devs, but very unlikely because of bandwidth costs.