RTF is a global modification that replaces all towns in the game.

*nitpicker arrived*
Actually, a Lich is a Mage-Necromancer who performed the Ritual of Eternal Night and became an undead Lich.
*nitpicker opened the window and ran away*

.*nitpicker #2 arrived*
It says here that it's UNDEAD that became a mage - there was no Ritual of Eternal Night, and they didn't practice necromancy in life; it's just a skeleton whose soul managed to overcome the self-awareness block.
This is the land of the dead, not necromancers; it's a Dark Souls branch in our Middle-earth.
*nitpicker #2 jumped out the window*