As I have said before, I am no expert in intellectual property law. But I am able to shed some further light on some of the questions raised here - with regard to UK law at least.
As far as literary works are concerned, copyright only protects the expression of an idea, not the idea itself. However, the borderline between the expression of an idea and the idea itself is very difficult to define. I believe that copyright does protect more than the story as written. For example, it is possible that ideas that are substantially elaborated could attract copyright protection. This might well mean that protection is extended to the concepts used by Tolkien in creating his tales.
It is also worth noting that copyright does not protect names or titles, so authors are free to use the names "Bilbo Baggins", "Legolas" etc in their own works. I suspect, however, that if such names were used in conjunction with characters identical (or substantially identical) to the characters they denote in Tolkien's works, this would constitute an infringement of copyright. Also, names and titles may be protected by trade mark law. I do not know whether the Tolkien Estate has trade marked the names used in his works, but I am pretty sure that they will have been trade marked in connection with the merchandising rights (which Tolkien sold off, together with the film rights).
The upshot of all this is that, if one were to publish for commercial gain a tale based on
LotR or
The Hobbit, one would have to tread very carefully indeed (in the UK and other countries, such as the USA, with strong intellectual property laws, at least). One would have to substantially alter the characters, locations and concepts in order to avoid being at the wrong end of a lawsuit brought by the Estate (which, as has been said, is very aggressive in enforcing its rights). Indeed, the closest one could get would probably be something akin to the Shannarah series by Terry Brookes.
As for the ICE role-playing guides and the more recent Middle-earth based role-playing game, I suspect that the rights to these were sold off by the Tolkien Estate along with the film and merchandising rights. In fact, they are probably included within the merchandising rights. This would account for the preponderance of Middle-earth based board games, card games and video games.
Finally, copyright in a literary work (under UK, and indeed EU, law) lasts for for the life of the author plus 70 years from the end of the year in which he/she died. Copyright in all of Tolkien's works will therefore not expire until 2043 (by which time I shall be in my 70s
).
Hope that helps.
