One of my favorite games of all time, and in my opinion, one of the best games ever made. It practically made my childhood and teen years. I used to play this for dozens-no, hundreds of hours on the original Xbox. It has a fun, funny, and engaging campaign that has you hopping from time period to time period, and the multiplayer is on par with major franchises like Halo. Many interesting maps to play on and characters to play on, and the weapons are a definite highlight. I would LOVE to be able to play this game again, and I would also love for people who didn't get to play it when it first came out to be able to experience it.
Minor spoiler for a funny/interesting moment:
At one point in the campaign, you're fighting zombies in a haunted house and you come across a deer head mounted to the wall. Suddenly, a zombie creature with a deer head bursts through the wall and bellows "THE MOOSE IS LOOSE!"