Standalone networking system?

Hi, I am wondering if I can make a standalone player which can than download all the information from a HTML. Is this possible with unity? I am making a game which you can play online and offline. So I want it like,

Player downloads the standalone, Player can connect through multiplayer and play online through the standalone. If player can't connect to the web, He/she can player in offline mode.

I'm just wondering if this is possible, Thanks in advance!