The Matrox Mystique PCI is a graphics card that was released by Matrox in the late 1990s. It was primarily aimed at users who needed a decent graphics solution for both 2D graphics and early 3D rendering, with support for PCI (Peripheral Component Interconnect) slots, which were standard in desktop computers at the time.
Windows driver for the Matrox Mystique PCI card, it is most likely because you are either restoring an older system, using legacy hardware, or dealing with specialized applications that require the specific functionality of this older graphics card.