[MoSattler]

Once everything is downloaded and archived, will this enable me to play the game without it having to talk to the steam servers?

[madeofpalk]

Depends on the game. Often the main exe still launches steam for bootstrapping.

[RunningDroid]

IIRC, this is mostly because the example for initializing the steam API library causes a crash when the library isn't available. As a result, a fairly common "crack" is to drop in a DLL that provides dummy functions.