Arx Liberatis
"Arx Libertatis is a cross-platform, libre port of Arx Fatalis, a 2002 first-person role-playing game / dungeon crawler developed by Arkane Studios. Arx Fatalis features crafting, melee and ranged combat, as well as a unique casting system where the player draws runes in real time to effect the desired spell."
http://arx-libertatis.org/