Spookiest game ever.
Shadowman is a LOOOOONG and drawn out game. I suggest using a walkthrough to guide you, because if not you will wander the dozen or so areas in this game aimlessly, just looking for one of the hundreds of "souls" you have to gather. It can get frustrating. There are ways to upgrade your character, named Michael LeRoi, and you need to do that in order to reach some of the souls. The only problem is, it's not really clear what you need to do next, EVER. That's why a walkthrough is important. It may take away some fun of the game, but it will also take a way a TON of frustration.
Overall, if you're one of the few Dreamcast owners, and you can find this game relatively cheap, it's a must try. What it lacks in gameplay at times, it makes up for in originality and eerieness. It will occupy you for hours, although it will get you frustrated at times.