Why the game hasn't been announced for Virtual Console yet:
Golgo 13 is a license; the game is based on a manga series about a hitman who isn't a hero, but forces readers to root for him because he's so damned awesome. While the character is popular in Japan, there's almost no point in renegotiating the license to release the game in the United States. For that matter, we can't understand why Vic Tokai originally bothered to release a licensed game based on an unknown character. Or how people like us convinced our parents to buy a game with a contract killer as the protagonist.
Why we think it should be on the Virtual Console:
Top Secret Episode switches rapidly between game types: side-scrolling action (with lanky, rectangular, ugly-yet compelling sprites; a sort of light-gun mode where you move a cursor to shoot assassins and helicopters; some light shmupping; first-person mazes; all capped by barely-interactive cutscenes where you get your final target in your scope and pull the trigger. These levels carry you through an international-intrigue plot that still manages to be sort of coherent despite the typical NES-game translation.
After a while, for us at least, you start to get used to the controls for all the different segments and start to get into it; the weird sprites start to look very much like a stylistic choice; and, should you manage to finish the first whole level (by making a map on graph paper for the first-person maze, no doubt) you might start getting into the story a little. Somewhere, along the way, you may realize that Golgo 13 is incredibly cool despite its faults.
Interestingly, this game, which slipped by 1988 Nintendo somehow, may be too adult for 2007 Nintendo. Not only does Duke Togo (Golgo 13 is his code name) kill people for money (and not just bouncing coins that their blinking corpses leave behind-- Golgo receives money from a third party for his kills), but there is one infamous scene that the ESRB is unlikely to miss this time around. Early in the first level, Golgo meets a woman in a hotel room who provides him with information related to his mission. She tells him that he should come back when he has the time.
Upon the return visit: "You know, Duke ... it's such a beautiful evening and yet ... out there ... Berlin at night ... an iron curtain just doesn't seem right." The scene changes to an exterior shot of the hotel; two figures are visible in silhouette; they move toward each other, and the scene fades out. A surprisingly well-done, mature scene, especially for the time and for the fact that, again, this is a licensed NES game, and not really a first-tier one. It makes GTA's "adult" content seem like a step backwards.