A mix from uplink, OpenVPN (something like hamachi) slave hack and some real life hacking.
Your computer will have a gig or 2 sectioned off for the game. Most of which will not be used for a while.
Players would issue themselves with a username and password and are given a virtual IP (which can
be changed)
Your computer will host a virtual computer, it will have its own upgradeable virtual hardware software and GUI OS (probably similar to windows).
Standard virtual hardware would be given to players as they 1st sign in. This hardware would be upgradeable via an in game shop and auction Much like in Uplink.
Virtual Software could be both pirated or bought "legally" in the game.
Computers would each have their own log file(s) a Log manager could be purchased to keep them in order or the user could watch them individually.
You must be connected to the games P2P Virtual Private Network to play (this is what OpenVPN would be used for).
Credits could be earned with fake wares and mailers
An in game anonymous chat room for players to play, taunt and chat.
The ability to make pop ups on others computers (while in the game)
The game would be able to run, full screen, windowed and in the background.
Its a real life, enclosed hacking game where the possibilities are only bounded to your computers power.