- Perhaps the Ur-Example: Atari's 1975 coin-op Anti-Aircraft. Cutting a particular trace on the motherboard would turn the airplanes into UFOs.
- Touhou Double Dealing Character has some unused swimming sprites for the 2nd boss and Embodiment of Scarlet Devil has cut character stats.
- 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.
- Numerous bits of cut content were found in Cuphead, including half-finished bosses (that seem like they were originally going to be part of the King Dice Boss Bonanza) a few extra weapons, and a unique death screen for dying in the tutorial (which is impossible in the current release without hacking.)
Dummied Out / Shoot'em Ups