Quoted from raven-games.com:
"ShadowCaster was done in 1992-1993. We started off doing it for EA and it was to be Black Crypt II. After we had the game designed, EA bought Origin and felt that we should take advantage of the Ultima World and make it some type of Ultima game. We started to turn it into an anti-Paladin Ultima game. Then it was decided that perhaps we should make it into a Bard's Tale spin-off. But that too fell by the wayside, and finally we came up with the idea of morphing a character into different types of creatures that had different abilities. We licensed a pre-Doom engine from id and we were underway with ShadowCaster. I must add that I really loved the concept for ShadowCaster, but hated the story and the name, and wish I could go back and redo it!"
- Brian Raffel
You can find the solutions of the two new levels added in the CD-Enhanced Version of Shadowcaster (Level 24 and 25) in the "shadowin.pdf" file in the "docs" directory of your Shadowcaster CD. Added as an addition to the Shadowcaster clue book.
ShadowCaster used a heavily modified version of the Wolfenstein 3-D engine, licensed from id Software and written during the summer of 1992. The original ShadowCaster was published in 1993; this makes it the first commercial game released with classic "2.5D Doom engine" improvements (distance fogging, non-orthogonal walls, textured ceilings and floors) before DOOM itself came out.