When using Tolkien's universe as a game setting, there are two major constraints; the geography, and the history. Obviously, Tolkien never intended for his work to be used for role playing games; he wrote simply because he wanted a context for his languages (and to tell stories, of course). Consequently, he only "discovered" as much of Arda as he needed for these purposes - which makes for a realtively meager geographical gaming context; with only a handful of documented settlements and hotspots to play with, environments are bound to get old fast. On the other hand, the vast portions of empty space on the maps leave plenty of room for players to come up with interesting places of their own - which is also what Iron Crown Enterprises (ICE) does in Middle-Earth Role Playing (MERP). But in the end, there is only so much you can add to the setting and still keep it intact. Which leads to the second hurdle; the history.

In Tolkien's Middle-Earth, all global events of epic proportions have either already taken place, or - as in the case of the time setting for MERP (which is ca year 1600 Third Age of the Sun and onwards) - are still to come. Important and fantastic things will happen - regardless of what the players do with their characters. Role playing in the Star Wars universe is a good example of the opposite: there is enough space for players to act out and have an impact on the setting without contesting the original. MERP still does its best not to turn players into bystanders, and the overall result is satisfactory. ( )