It's my personal favorite of that particular subgenre. I was a huuuuuge fan of that kind of crawler - back in the day.
It had some amazing "boss fights" - where you had to figure out specific and relatively logical ways to beat them.
For instance, I remember fighting the Medusa - which would kill you by turning you to stone if you looked at her. So, you had to find a mirror and figure out how to force her to look at herself
It also had one of the very first underwater environments in that kind of game, as I recall.
An amazing title - and it's still Raven Software's best game - followed by ShadowCaster, which was their next title. Ironic that their first two games were - by far - their best ones.
How the mighty have fallen…..