A best-selling, thick novel, turned into an equally successful TV mini-series some years later? Put into the able hands of Infocom, who had already proven their talents at literature adaptions into an interactive medium with the widely acclaimed The Hitchhiker's Guide To The Galaxy? The subject matter clearly falling into the adventure genre, the very same which gave this type of computer game its name? Must have been a match made in heaven.
Unless you look into the details of how this game came to be. By the late 1980s, Infocom had ceased to be the independent, stellar company they had been at the time of making Hitchhiker. Parent company Mediagenic (Activision) had acquired this licence without even consulting them. And unlike Douglas Adams before, James Clavell showed no interest in actual collaboration on the game. So Infocom veteran Dave Lebling, who had shown he really still had it with the excellent original creation The Lurking Horror, took an approach which was probably the best one imaginable given the size and complexity of the source material coupled with the lack of external guidance: he made Shogun an episodic, sort of "highlights from the novel" game.
Meaning the player is served with 19 stand-alone scenes of varying length, between which no global state is tracked. No inventory items are retained, previous foolish actions are forgotten. Writing is generally colourful and strong, with central passages just being copied verbatim from the book, but plotting is globally almost non-existent. Or at least it's hardly possible to follow without prior familiarity of either novel or TV version. Lebling shows an eye for picking the right scenes to sort of work in such a self-contained manner, but they remain almost as meaningless vignettes.
Worse, the translation into this interactive medium fails to a significant degree. Although the amount of actions understood by the parser remains on an impressively high standard, this understanding is not really applied to any end. Too many of the scenes can only be called pseudo-interactive at best. Often, there is another character telling the player exactly what to do… and guess what, this is not a tricky puzzle, for example to pretend to follow orders while actually working around them – the correct solution is to just follow the orders. Attempts to diverge resulting in swift death or the dreaded "this scene is no longer winnable" message (effectively the same as death).
Other scenes offer more freedom, but whether for the better remains questionable. These scenes suffer a lot from the expectation to be able to read James Clavell's mind (or having read his book). Required actions mimick those of the book's protagonist closely, but as the situations appear inherently in-game, there is often little indication why one should try this of all things. Giving the sour feeling that one has to do these things simply because it is the way it is and not because it makes sense.
The overarching theme present in most scenes, being mostly helpless in a completely alien society whose rules one is unfamiliar with and where an incomprehensible language is spoken, makes up for some pitfalls. Same for the occasional graphical illustrations, nicely drawn even if not up to the best standards of the time. Infocom chose another way of integrating them than the main competition: instead of permanently displaying graphics in a sort of "frame", they are scrolled along with the old text. This allows for more screen estate to display text once the player has seen and appreciated the pictures. Unlike in Zork Zero, however, the graphics do not fulfil any gameplay purpose (with one exception).
Shogun is neither the huge catastrophe some make it out to be in retrospect, nor the overlooked gem others claim it to be. Negatively, it could be seen as an indicator that Infocom's star was really sinking by this time. Positively, in context of their other final releases, one could say they were doing their best to experiment, trying to see where and how to break new grounds. Since none of the attempts proved sustainable, we never got to see where things would have gone.