Cuphead (partially found cut early builds from 2D boss rush platformer; 2017)
Cuphead is a 2D boss rush platformer made and published by StudioMDHR Entertainment. The game has been praised for its heavily 1930s inspired cartoon style and is widely regarded as one of the hardest video games ever made.
The gameplay of Cuphead can be summed up with this: for run & gun levels, you run to the right, shoot everything in sight, and try to stay alive; while in boss battles, you shoot the boss, dodge its attacks and try to stay alive.
Although Cuphead was released in 2017, the game was delayed a couple of times. It was originally slated to be released somewhere around 2014, according to a teaser trailer released in 2013. It was originally going to be a "boss rush" type of game where you have to defeat each boss in order to progress, but it went through many development changes over time. Since its delay, most of the content from the supposed demo or beta either got removed or had been left out inside the game's files.
- The Devil Bat/M.Fang (can be seen in the E3 2014 trailer)
- Jelly the Octopus (can be seen in the video "Cuphead Gameplay" by Tom's Guide)
- The Spider (only appears in screenshots, presumably wasn't made or never finished)
- Double Goopy (only appears in the teaser trailer)
- Pachinko (can be fought by debugging, it even had a death quote)
- Light (can also be fought by debugging, most likely a test level for an unfinished boss)
- Card (can also be fought by debugging, most likely a test level for an unfinished boss named "King Card")
- Betty Beet (only appears as concept art, the "knockout" animation of her can be found on YouTube)
- Triple Laser/Wide Shot (it fires three shots in one direction, it was replaced by Spread)
- Ranger/Exploder (can be seen on the teaser and the 2014 trailer, they're circular and explode when in contact with the enemies but when used in-game, they just pop instead of exploding, they're also different in terms of design)
- Arc (they fire in an arc, and they're shaped like stars, it was replaced by Lobber)
- Plane Laser (the only attack that can only be equipped using the Cheat engine, They look and had the same function as the peashooter)
- Arcade Peashooter (can be equipped with debugging, the game will softlock as soon as you die equipping the weapon)
- Shield/Pit Saver (they prevent you from getting damaged from falling into pits, they also extend your invincibility time)
- Turret (they would act as some sort of handicap for players)
- Woodland Walk (enemies from Forest Follies would be present in this stage, it had different platforms and background)
- Backwood Crusade (same thing as Woodland Walk)
- Tricky Thicket (the same thing as Woodland Walk, it would take place at night)
- Forest Frolic (no gameplay of it can be found though it might be the same thing as the aforementioned forest levels above)
- Arcade Tent (it's still in the final version of the game though you can't interact with it)
- Early Battle Starting Screen (it would say "Fight or Flight" instead of "Wallop!")
- Original Health Bar (it's basically a happy face that frowns when getting hit by an enemy)
- Original Loading Screen (it would read "ONE MOMENT PLEASE" instead of showing an hourglass in the final game)
- Timer (it would be displayed at the top of the screen while fighting a boss)
Although most of this content can't be accessed through normal gameplay, some of them can still be found in the game's files. It's possible to use them in-game by debugging the game or by manipulating the values of save files. As for the bosses, it's unknown if they'll ever return by means of a rumored sequel that has yet to be confirmed or they'll return in the DLC that's set to release in 2022.