Doug Limbardi is quoted as saying:
"During installation the user will be prompted to authenticate the copy and create a Steam account. After that is complete, the single-player and LAN games do not require an Internet connection."
If I remember correctly there was also a pre-release quote saying that Steam would require online authentication before you played for a couple weeks (and then after the first couple weeks HL2 would allow you to go right into Offline mode) but I cannot find this quote. Thanks for helping me find this
"During installation the user will be prompted to authenticate the copy and create a Steam account. After that is complete, the single-player and LAN games do not require an Internet connection."
If I remember correctly there was also a pre-release quote saying that Steam would require online authentication before you played for a couple weeks (and then after the first couple weeks HL2 would allow you to go right into Offline mode) but I cannot find this quote. Thanks for helping me find this