In order to unlock Edgar you have to collect all of the 106 Starites.
In order to unlock Julie you have to collect all of the 106 Starites.
Electrocute Maxwell while he is wearing an item that changes his vision (for example, X-ray Goggles, X-ray Glasses, Thermal Goggles, Nightvision Goggles, or Polarized Sunglasses).
To revert back to normal, play the mode you activated a second time.
Unlockable: --- How to Unlock:
Gameboy Color Mode --- Type in ARCADE MACHINE to get an arcade that can be played.
Gameboy Mode --- Type in VIDEO GAME to get a gameboy.
Old Timey Mode --- Type in TIME MACHINE, and use it to make everything sepia tone, and have a piano bgm.