The term "Secret Gambling Games" (also known as "Stealth Gambling Games" by MAME developers) refer to arcade games with hidden gambling functions. These games are usually unlicensed versions of other arcade games, including Pac-Man, Space Invaders, and Tetris, often with a drastic downgrade in gameplay, graphics and music. A switch is present in the games that switches the game to a gambling machine. Secret gambling games were often used in areas where gambling was deemed illegal, the arcade portion added to avoid action from law enforcement.
Some other illicit gambling establishments have also known to use a less practical setup involving two PCBs and switch system, one for a seemingly legal arcade game and the other containing the machine's true intentions.
Several versions of Cherry Master feature a port of Ms. Pac-Man, branded as Super Pacman (no relation to Namco's official Pac-Man sequel of the same name) with the maze turned 90 degrees to fit the horizontal monitor. One could argue this hardware was not designed to run action-heavy games like Ms. Pac-Man; the game runs incredibly choppy. Another version features Tetris instead. Using a secret input, the games will boot into Cherry Master (version 8.01 for the Tetris, and 8.31 for the Super Pacman version). The original Cherry Master games were made by Dyna based in Osaka, Japan, but these bootlegs were made by another company named Corsica and run on different hardware.
A video slot game created by the Taiwanese company Subsino in 1996 featuring marine themes; the game features a basic Columns clone as a disguise game.
A poker game disguised as an generic aircraft shoot-em-up game created by Subsino, dated 2006 according to the title screen. The game features one-button switch intended to be installed "at the secret area, where is most safe and operate easily" in regard to switching modes.
Space Invaders and Pac-Man
Also known to exist are Space Invaders and Pac-Man clones - the gambling mode reuses sprites from both games specifically. The company that made the games and their release years are unknown, although the games run on the same hardware as 4 En Raya - a Connect Four-type game made by the Spanish company IDSA. The Space Invaders game is extremely difficult, as the aliens' fire is almost too fast to dodge.
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- A gambling game called Crazy Bonus hides itself by using a Windows ME desktop, rather than another game.
- The game Blockout (TAX) in MAME is believed to be a secret gambling game, but due to its preliminary emulation, this is not yet confirmed.
- Similarly, the game Fruit Land (an original game featuring Pac-Man) reportedly has a gambling mode, according to several Ebay auctions, but no evidence of this can be found in its code.