Dummied Out / Shoot'em Ups

  • Perhaps the Ur-Example: Atari's 1975 coin-op Anti-Aircraft. Cutting a particular trace on the motherboard would turn the airplanes into UFOs.
  • Embodiment of Scarlet Devil's game data reveals a few lines for one "Rin Satsuki", who was cut for reasons unknown. Isn't it sad, Sacchin?
    • Early on in Sakuya's stage in Mega Mari (a Touhou-themed clone of Mega Man), there is another hallway underneath the floor. A Lyrica is down there as well as a ladder leading down, but there is no way to access it.
    • Double Dealing Character have swimming sprites for Wakasagihime that are never used in the game itself.
  • Metal Slug has a number of dummied out content within each game, with Metal Slug 5 being the most egregious. Ragey's site Metal Slug: Missing In Action documents the vast amounts of lost content there is in the series.
  • The Arcade Game Astro Blaster had a Sector 8 which would appear in the Attract Mode if that was left to run long enough, but can't actually be played because the game loops after Sector 7. This made Secret Bonus Number 20 impossible to obtain without hacking the game.
  • Astrosmash for the Intellivision was programmed as a compilation of two asteroid-shooting games, Avalanche! and Meteor!. Since Meteor! was a simple clone of Asteroids, Mattel's lawyers ordered it removed, but its code remained in Astrosmash, and a rare glitch could cause Meteor! to load when resetting the game. Meteor! was later reprogrammed to be less Asteroids-like and released as Space Hawk.
  • The cutscenes in Thwaite were originally supposed to have characters walking around, like during the game. Graphics for walking characters at cutscene scale are still present in the tile sheet.
  • Recca has a hidden intro buried in the game's code. It's probably a safe bet that someone didn't like SEGA very much.
  • The Japanese version of Elemental Gearbolt includes an unlockable audio drama of a plot point referenced in the main story. It is still present on disk in the English version, but inaccessible. The localizer, Working Designs, decided to summarize the story of the audio drama in the manual instead of reproducing it in English.