Double Dragon (Neo Geo)
A surprisingly decent 1-on-1 fighter, based on the movie. No, really.
Enable these via the Debug BIOS to achieve the desired effect:
|1-1||Makes it impossible for any character to turn around. If one jumps over the other, then they won't be able to change the direction they're facing unless they get hit by an attack or jump over each other.|
|2-1||Causes the fight to run at half speed. The background animations are also affected, but sound effects, music, and other animations and transitions are not.|
|2-2||Causes both players to be invincible.|
|2-3||Maxes out both players' CHARGE bar immediately.|
The arcade (MVS) version has two different sets of credits: one for beating the game without using continues, another if you do so after using at least one continue. The Neo Geo home console version (AES) only shows the "used a continue" credits, even if you beat the game without using a continue. As this video proves, the "special ending" can only be achieved in the AES version by beating the game in the secret "Professional" difficulty.