Keep multiple saves of your current level since some levels at the end will put you in a situation where you can't get back and must go on. There are several levels I only partially explored because of this. You lose the game when your spiritual health drops to zero or two guard simultaneously grab you. To regain your spiritual health, there are a number of scrolls scattered throughout each level. Running over these scrolls recovers some of your health and a scripture is displayed in the upper left corner of your screen.
Every scroll is a different scripture.
The Game is built around the Genesis 3D engine. It's probably the best non-commercial game engine available. The folks at N'Lightning have made very good use of it. Some of the images in Catechumen are stunning. Most are very good.