: GURPS says specifically the following: "The rivers
: around Rhi'anon ran red with blood during the Great
: War, but it is believed that Balor's practices created
: this effect rather then natural causes." (page
: 17) I don't know what that last part is suppose to
: mean, but it seems to suggest that those rivers are
: blood... if you believe GURPS that is.
Bodies of water in the area are red in Myth II as well, however, when Balor was no longer doing much of anything. Combine this with the TFL level names and it's pretty clearly rust.
--SiliconDream