In addition to the music already mentioned, a renditioned excerpt from "Dawn And Siegried's Rhine Journey" of Richard Wagner's Götterdämmerung is used in-game. It can be heard once Constantine reaches Camelot.
One can see that the developers of this game were heavily influenced, not only by Arthurian Legend, but also by the 1981 John Boorman movie "Excalibur".
This influence can be seen in the introduction of the game which features a shot of a tranquil lake at dawn (very similar to a similar scene toward the end of the movie). A few moments later the Lady of The Lake's hand rises above the water (clad in the purest shimmering samite) wielding the sword Excalibur. The sword itself is very similar (if not an outright facsimile) of the Excalibur sword from the movie. As the intro plays, it is accompanied by a rendition of "Siegfried's Funeral March from The Ring" from Act III of Richard Wagner's opera Götterdämmerung, this same piece of music can be heard in the film Excalibur.