This is a weird and interesting game, which tells an important story in the history of mouse-look. The developers were experimenting with control methods which seem clumsy by today's standards. However, there is a control method which can be enabled in the options which roughly matches modern standard third-person movement. It's not enabled by default and unfortunately the mouse movement is very erratic on modern machines which means a modern tidy port would be very useful for preservation purposes. The game doesn't handle widescreen well and resizes windows on the deskop while it's running, which makes running it painful.
I played the Vigilance demo on a cover disk but I don't remember ever seeing it in the shops in the UK. On eBay, all copies of the disk are from America. I wonder if it was even released outside of the US? What I remember most about the demo was the atmospheric use of light and shadow in the level. It's realistic locations echo Alpha Protocol, decades later.