Spitfire (Fairchild Channel F)
This game has hidden developer credits.
Spitfire is an air combat game just like the plane levels in Atari's Combat, notable as having one of the oldest Easter Eggs in gaming. It doesn't work on a standard cartridge, unfortunately, though it works properly on a multicart.
At the "G?" game selection prompt that appears when the game is booted, normally the player presses 2 on the Channel F's front panel to start a one-player game or 1 to start a two-player game (yes, it's backwards). 3 and 4 do nothing... or so it seems. In fact, pressing 3 initiates an invisible routine that checks for a passcode: 343242124133231432142314322132342334111223324443. Yes, that's 48 button presses, which must be spaced apart enough for the Channel F's primitive CPU to register them. The screen will flicker for each successful input. If the wrong button is pressed, the game will briefly blank the screen for a second before returning to the "G?" prompt; the player must press 3 to start the passcode routine and try again.
If the code is successfully entered, the following developer credit appears on the screen for a split-second, just long enough to be read:
In total, all of the code related to the routine, including the passcode itself and the graphics for Glass' credit, takes up 226 of the game's 2,048 bytes or 11.04% of the ROM, with just 140 bytes of empty space left on the cartridge.