The story of Doom takes place several decades into the future. You are a Space Marine, posted at Mars. The Martians have recently been experimenting with inter-dimensional travel, and have even managed to invent a teleportation device. One day there come distress call from Phobos, one of Mars' moons - terrible creatures have been appearing through the dimensional gateway. Not long after, contact is soon lost and things don't look to bright at Phobos. You are sent there to investigate and soon find out that all of the moon's team have been transformed into mindless demons. Not only that but other terrible beasts have wandered through the portal. You single handedly must find out what has happened and put a stop to it before things get out of hand.
Doom makes its predecessor, Wolfenstein 3D, look like a pre-school picnic in all regards. Step around the corner and you are often greeted with a room full of demons, ready to turn you into mince-meat. Step onto a floor panel and watch the room explode in violence. Chainsaw a barrel and watch yourself see the room turn red. Watch bad guys (or yourself) slide down the stairs dead. Curse as a demon appears next to you on an elevator. Run through the darkness as the lights flicker, invisible demons pounding you in the darkness.
There are your standard assortment of weapons to be gained along your way - the chainsaw, pistol, shotgun, chain gun, and the most powerful in the shareware version, the rocket launcher. In the registered version you also get to gain control of a Plasma thrower BFG9000. Probably the best all-round weapon is the shotgun, though the other weapons come in handy in certain situations. There are also other 'bonuses' such as an automapper, armour an invisibility helmet, light helmet and lots of other goodies which can all help you out many times during the game.
All in all, Doom was one of the fastest and most exciting three dimension action games ever seen at the time. It contains everything that makes up a good game: plenty of action, plenty of difficulty, plenty of suspence, quality artwork and audio. It is the pinnacle of early 90s gaming.
Doom II requires no introduction. It's predecessor was ballyhooed almost a year prior to it's release, and exceeded anyone's expectations. Doom was the largest reason for loss of productivity on networked machines in the United States. No one had seen anything remotely like this before and the sequel was eagerly awaited.
As for the game itself, the premise is that the player is continuing on from the last episode of Doom (Inferno) and is fighting evil on earth itself. The goal is to get to the last level to "flip the switch" which should banish this hellish horde back to whence it came. Many new monsters (like the one that shoot lost souls at you) fill out the thirty levels. The individual levels are thought out much better (I love the level which you drop through the floor to get to the next level), and the textures are used to full advantage.
One item seen throughout the game is that the lighting is a lot more dim. You can use the gamma correction key (or even the light-amp cheat key sequence) to help, but I feel that it does detract from the game a bit. All but one of the key cheats that were found in the original are intact. Also, you get a new "super" shotgun that does a great deal of damage at the cost of additional shells.
All of the thirty levels (plus two secret levels) have great designs. Some worried that the plethora of add-on levels available for Doom would decrease the value of Doom II; they were wrong. Doom II's levels are extremely well designed; it is obvious that id spent a lot of time on them. The graphics are defined and colorful. Some of the most notable are the new outdoor and sky scenes. One of my favorites is the city in the background which was breathtaking given the technology of the mid 90s. The new textures and enemy graphics really give a whole new feel to the game. All of the new enemies look even more realistic than the old enemies did in Doom.
Snarl. Growl. Grrrr. Scream. All of these sounds were trademarks of Doom. Who could forget the Marine's scream at his death, or the Imps' growl that always made you jump? Doom II added more of these great effects. The snarls are scarier, the growls more realistic, and the screams more frightening. I almost wonder if id did some sound sampling at P.O.W. torture camps. The music is what really pushed me over the edge. Ominous and thrilling are really the best two descriptions for it.