Words cannot express just how epic this game is.
Doom is a game unlike any other. More to the point, if you think there is, it is more likely those other games are like Doom. For Doom is one of the pioneering games of the FPS (First-Person Shooter) genre.
Doom pits you, a lowly space marine grunt, against the denizens of hell, who have somehow found a way through to our universe via teleporters on Phobos, one of Mars' moons. Hordes and hordes of demons stand in your way, and your goal is to eliminate them and seal off the threat before they find a way to Earth. With your squad slaughtered, you are totally alone.
FPSs are typified by the first-person perspective, a minimal HUD (Heads-up Display) and everything you see on-screen is exactly as if you were looking out of the marine's eyes. Your currently equipped weapon is held before you, emerging into view at the centre on the bottom of the screen, and your health and armor and ammo are also seen out of the way at the lower edge.
While the graphics aren't on par with the games of today, they do a good enough job. Most everything is pixellated as hell on the resolutions of today, but that isn't why gamers come back to it, or the reason it is a classic. It's the sheer fun of wielding big weapons, killing demons, the rush of having a trap spring on you and having to fight your way out! It's the refreshingly simple controls - moving, shooting, changing weapons, activating doors and switches.
The game is divided into three maps, and each map has its own assortment of levels, and a secret level. Interestingly, and this is an idea that no one else has picked up on that I know of, choosing a higher difficulty makes more of these maps become available. For example, "I'm too young to die!" will not let you play the second and third maps.
Your first weapon, the pistol, is the most unassuming weapon of all time. Yet, your ammunition is not infinite! Yes, it is possible to run out of ammo on every weapon in Doom, and be reduced to a gibbering madman hiding in the corner with his pair of fists, or chainsaw if you were lucky. The range of weapons available over the course of the game is considerable, each offering their own pros and cons. The shotgun makes a handy primary weapon, but the bigger foes might need the rocket launcher, or the plasma cannon. A trademark of the Doom series is the BFG. How best to explain ... I guess it's like a tank, only you can strap it over your shoulder. It stands for Big *Bleep*ing Gun. Enough said.
Monsters and demons also have great variety. I could explain them in great detail, but I'd rather you just read the manual - it's good for a chuckle and a grin, and highly accurate. There are various enemies that fire bolts of energy from afar, and before you know it, they can be right in your face, chomping or rending your flesh. Even their hellish roars (a common occurence, they do it when they see you) are unique.
Doom incorporates some of the most fun gameplay you are likely to ever get from a shooter. Sure, textures and resolution are important in a game, but what Doom has, it makes good use of. So what if a corpse looks exactly the same from every angle? Perhaps on some level they are still alive, turning their bleeding broken corpse around with a sinewy claw, still trying to get at me.
It's a gory glory to all things demonic and satanic. It's a classic. Better still, it's DOOM. Do you have what it takes to out-master a Mastermind?