i had this problem:
- updated steam
and the 'error' they told they have fixed , appeared for the first time (and kept on repeating) on my screen. Something about the "Game is not available". (CS), I tried. any other mod i had installed, no luck.
Anyhow, what made it work:
- i looked to half-life engine.cfg; removed it.
- i replaced that file with a version of a friend of mine and it worked (since he got it running).
So if anybody has trouble with this, grab a working "half-life engine.cfg" file at (5MB zipped!)
http://realbot.bots-united.com/files...e%20engine.zip
To install:
unpack it into steam/steamapps.