Well Steam offline mode is working for me today...
test #1: network cabled plugged in.
Launce Steam, it logs in and runs in online mode, I start esf open beta and "create server" (LAN game)...
SUCCESS.
(closes Steam)
test #2: network cabled removed.
Launch Steam, tries to update but it realises there is no internet connection.
Asks me if I want offline mode, I choose "offline mode".
(this time Steam lets me launch in offline mode without needing internet access to the Steam network :] )
I start esf open beta, "create server", no settings changed, (LAN game)...
FAILED.
repeat test #1 as many times as I like...
success
repeat test #2 lots of times, every time...
failed
So, can other people play ESF Open Beta with Steam in offline mode?
It's a good thing I haven't thrown away my 2 counter-strike CDs and 3 half-life CDs...
I don't always have access to internet on my laptop.