I seem to recall that Scrabble's board layout could be an issue. The specific placement of double/triple word/letter squares is not merely an important game mechanic, but also a distinctive feature of the brand. There's also the question of letter-tile point-values, and whether those specific points could be copied verbatim.

Source: I played a MUSH where players managed to reproduce games like Boggle and Scrabble for the amusement of other MUSHers