Perhaps when linked in you are in the same world as everyone else, but you now see it from the perspective of information. Code gates on buildings, ICE at the door,, camera remotes, people walking by with little flickering lights where their neural processors are.
In this method, you wouldn't have to create a different game environment, just swap out the visual display and HUD. The same elements are present in the game environment either way, but you can't see or interact with them unless you are jacked in.
So you jack in, open your eyes and the Menu pops up. You look around and that previously inaccessible casino in the middle of the block, all steel, chrome and turrets in the real world, is now a resplendent neon-painted yellow/green building in the Net. High up, about the third floor in the Real World, is a door guarded by a Minotaur. The door has the number 7 on it, indicating it's complexity to your Deck. Nearby cameras and turrets are rendered in pale red and as your cursor travels over them, the Menu flickers, indicating it can interact with them.
You tap the space bar and float up a level, and again until you are even with but a safe distance from the Codegate. You flick through your Menu options and pull up your list of cracking programs. Opting for stealth, you launch a Worm, a long white undulating thing crackling with blue energy. It snakes along towards the Gate, passing quietly behind the suspicious Minotaur, until the Worm reaches the Gate and plunges it's head in., followed by it's long, wriggling body.
Just before you turn your attention to cracking the not-very-complex numbers puzzle the worm offers you as it's find, you glance up and see the distant shapes of military and corporate systems, great glaciers of forbidden power and black ICE, fatal to the unprepared. Some day, you think to yourself.
Some day,