On April 29, 1989, Operation Wolf was put on the infamous German index by the BPjS. For more information about what this means and to see a list of games sharing the same fate, take a look here: BPjS/BPjM indexed games.
If the Tandy/PCjr or CMS/GameBlaster sound modes are being used, then in game sound effects are played through the internal speaker and music is played through the sound hardware. In Adlib mode both music and sound effects are played through the sound board.
Originally "Operation Wolf" was a coin 'op game, developed by Taito in 1987. The machine was a huge success, followed by "Operation Thunderbolt"
In 1994, the developers published an "Operation Wolf 3" slot machine. The gameplay was exactly the same as in the first part, but had a special mission at end of each level.