The player takes the role of Kirt, a human with powers of shapeshifting. Among other forms, Kirt can become a huge cat-like animal, a floating tentacle-wielding gazer, and a dragon. In the beginning of the game Kirt finds out that he is not in fact human, but comes from a parallel world where there was a war raging between shapeshifters for centuries. Kirt, and his grandfather, are the last of their kind, and now the evil ones have found them. Kirt's grandfather opens a portal back to the homeworld, and that is where the story begins. Kirt's mission is to stop the demons once and for all, but first he will need to awaken his innate shapeshifting powers, which is where the obelisks come into play. Going up to one of these and touching it will unlock a new form, and the first is the cat form. Few video games have made the concept of shapechanging the center of their gameplay, Kameo: Elements of Power is a rare example of a modern game based on this concept.
The Shadowcaster game engine, a successor of the Wolfenstein 3-D and a predecessor of the Doom technology, was written by id Software's John Carmack and licensed to Raven Software. Carmack wrote the Shadowcaster 3d engine during his technology research after id completed Wolfenstein 3-D. The engine features diminished lighting, texture mapped floors and ceilings, walls with variable heights and sloped floors. The engine was "about half as fast as that of Wolfenstein" but fit the exploration of Shadowcaster rather than the fast paced action of Doom.
The main character of Kirt was based on the name of the game's software developer, Kurt Schallitz, and included his brown leather jacket. The face of Kirt is actually that of Raven software's owner Brian Raffel.
Maorin - The first form the character collects, and the most useful early in the game. Maorin is a large four-armed cat like creature with superior fighting ability. It drowns quickly however.
Caun - A leprechaun like creature who is a poor fighter, but can heal quickly, jump over obstacles, fit in smaller spaces and can unleash a swarm of insects (needed to unlock a particular door).
Opsis - A hovering eye with tentacles that can use magic effectively.
Kahpa - A decent fighter that can breathe underwater.
Ssair - A hovering dragon with no legs with better attack (but weaker defense) than the Maorin.
Grost - A man made of stone that is an excellent fighter with strong defense that can also punch through certain walls.