Start-Up - Turn on Power, Access pack-a-punch, and activate Rushmore
Population - Kill zombies until the Nuketown sign has a population of 15
Clock - There is a giant clock behind the Nuketown sign that you have to wait for to hit 1.
3279 - Put this code into Rushmore to get a 5-minute undead man walking.
Purple Orb - Open up the shed in the backyard of the Yellow House. Follow the orb until it flies away in the APD Interrogation room.
Screen Break - Go buy that Bowie Knife in the Generators room. Go back to the screen and melee it. A code will then print out, make sure to remember this code.
Round 200 - Once you are ready with everything that you have you will need to type in the code into Rushmore. You will get teleported to the Cul-de-sac and whatever was not Nuketown is blocked off and advance the round to make it to round 200.