Shadowcaster

Shadowcaster is a first-person shooter/role-playing computer game from 1993 developed by Raven Software.

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.

Shadowcaster's game engine is an early prototype of the Doom engine, with support for height differences in the ceiling. It also has a few features that Doom does not, such as sloping floors.