Okay, this is a read the manual game. Also, have a pen and paper handy for writing that access code at the beginning of each level down, or you are hosed.
After that, it's a badass, hard mode TRON game that captures the "chase," feel of the Sailor's tip to the heart of the system while being ever vigilant of the dangers on route.
Phase II involves putting things in a binary code. Again, write this stuff down. It's timed.
But this game, unlike others of the era is *winnable* and you actually get a Kevin Flynn screen printout victory message for your trouble if you manage to beat this thing.