Doom is the product of time and culture, a product of pure passion and technological advancement that has reached a point of near immortality. The music, the imagery, the pace - everything is so tuned perfectly.

Beyond the gameplay and the music - the technological advancement as well - you've got without a doubt a game that's easily secured it's throne atop the mountain. Not only did Doom inspire thousands of imitators, it gave life to a genre and gave it identity - to which others have built on. I'd easily say without Doom the game landscape would be vastly different, more so on the PC side of things.

We've all seen it, or played it before - you know what it is - buy it. You don't need another recommendation atop a glowing Everest-scale sized pile of them. But here's another - PLAY IT.
You don't need me to tell you, you know.