The Watchmaker by Got Games Entertainment 2002
From the back of the box: The Watchmaker is a 3D real-time puzzle based adventure game set in and around an ancient castle in present day Austria. Join London lawyer, Victoria Conroy, and paranormal expert, Darrel Boone, on their mission to foil the plans of a fringe group of religious fanatics. The goal is to recover a mysterious pendulum device that could be used to destroy the world.
This was a replay from a quite a while back. I have to admit the interface was little clunky but it really didn't take away from the game. You had two independent characters that you could switch back and forth to and swap inventory items with each other. You got to climb, push, run and jump. You can die! The story was fun to play out in the castle. Speaking of the castle, it was big with lots of rooms. There were secret rooms and towers and dungeons. All that good stuff. I spent one evening just walking the castle to figure out where all the rooms were and how to get to them. There was a lot of question conversation with other characters. It's a pretty long game and would be really long without a walkthrough.
I played this on my old Windows ME computer with no problems at all. You could probably find it on Ebay for a cheap price. It would be worth the money. For me, this is what the old adventure games were made of. I enjoyed it very much.
I took some screnshots and grabbed some music that you can see and listen
Here