In a recent Twitter post, Hideo Kojima talked about taking on a taboo in the game industry. Leaning on the side of this being a gameplay taboo (and not content), what do you think a taboo could be?
To be honest I can't really think of any way you can really break a gaming taboo, unless the golden rule is that the player must always have fun and the taboo is to deliberately want to rob them of that. A book or a movie does not have to be fun or entertaining to be considered "great". Indeed, most great works of literature as well as movies are not always entertaining, unless you like being challenged. But entertainment is so integral to the concept of a video game that doing something that works against it deliberately is the only taboo I can think of that would really get one fired, or angry enough to destroy your fanbase to warrant being fired. There is a precedent for this, however. Lucasfilm Games, before becoming Lucas Arts, released a game called Maniac Mansion
, a game which had several deliberate red herrings and situations that implied solutions for puzzles that had no solutions, frustrating many as they tried anything on everything to solve puzzles. Even though the game could be finished it was more difficult than it normally would have been because of this. Not many people seemed to mind because, if anything, the old 1980's type of adventure games had a knack for people being stuck on a single puzzle for weeks, so it came with the territory. Lucasfilm Games was also a very small company back then when creating games were relatively cheap. But in today's game environment for a high-profile internationally renowned designer to make a multi-million dollar game where frustration is part of the experience would be career suicide if the public and press react negatively to it.
Edit: This is so counter-intuitive that I consider this explanation to be highly unlikely.
Either that, or "gaming taboo" for him would just be writing a very simple story. Something like two jobless people riding trains all day to pass the time and reminiscing about life in general. Press Y to gesture and X to pick up cigarette stubs.