Heretic ][, originally produced by Activison and now ported to
Linux by Loki Software, is a weird beast. Using one of Quake's 3D
engines with a lot of extras (pole-vaulting, mana systems, magical
weapons and defense shields), the game excels in pleasing the eyes
and ears.

This is the free demo version - a full version is available from
Loki Games at http://www.lokigames.com/products/heretic2/