Back in the late nineties/ early 00's, my dad had a gaming computer. On this computer were several demos and videos of games. One video was first-person, and had a knight entering a basement. He draws his sword, swings at the air a few times, then climbs down a rope into the basement. In the basement is a green monster/zombie. The monster moans and groans, the guy tries to run away, ends up getting killed. I know that's not a whole lot of info, but it's all I remember. Help me find this game, so I can finally resolve this great mystery of my childhood.