Side Arms Special was released on December 15, 1989 exclusively in Japan. This version featured an arranged version of the original soundtrack composed by Alph Lyla. In addition to the standard game mode from the TurboChip version, the CD version also features a "Before Christ" game mode that changes the game's rules completely. In BC Mode, the player can only change their weapon upon picking a power-up, only Combination Alpha is available, and the Mega Bazooka Launcher can only be used by holding down either fire button to fill the Laser gauge below the screen and launch it.
Source: Wikipedia, "Side Arms Special," available under the CC-BY-SA License.