Doom 3 takes the premises of Doom, such as plot, setting, and monsters, but beyond that this is a very different game. Obviously they've had a lot of time to improve the graphics: everyone says they're great, and it's true. Unforgivably, skin is rendered like plastic, but other than that the game's graphics is just a step or two below a CGI movie like Final Fantasy. There will be moments you will say 'wow', or later, 'dear god'. If you have the hardware for it, (for geeks like me) the game is worth getting on the merits of this alone. One big improvement the graphics engine has over all other games is its treatment of lighting: no longer is there that awful, unrealistic 'ambient' light you see in just about every 3D game. In all the 'dark' games I've played (including the original Doom), you could just turn up the gamma correction to see what was going on. No longer. Now, if some place isn't lit, it's black and that's all you're going to see. This contributes greatly to the scary atmosphere as well as difficulty.
And difficulty does depart significantly from the originals. Doom I and II had a Nightmare difficulty which was somewhat impossible in places, but the 'normal' levels underneath it were quite doable to the point of being still fun, but not especially challenging to a veteran gamer. Being pretty good at games I naturally chose the 'Veteran' difficulty, and got beat silly, especially in later areas. The game designers obviously thought of ways not only to scare the bejeezus out of you, but also to make it hard. Enemies are fewer but don't go down easy, especially if they get a hold of you first. Sometimes you end up having to adopt unconventional tactics, like running and hiding and scaring the demons with your own blast when they find you, or even eluding them completely when possible to save ammo.
At least for a while, this can make the game quite satisfying. But as the game wears on it becomes obvious that the game's design centerpiece, to scare you, no matter how well done, can get old. Sure the moments don't stop where you get scared because a demon climbed up a railing behind you, or something jumps right into your face when you turn a corner. But you learn to expect what start to feel like predictable cheap shots, and eventually find yourself automatically turning around when you hear something in front because you know chances are they dropped more baddies behind you too. That there isn't more variation to break the scary-darkness theme up is a pity because it would have allowed players to relish it all the more, especially given the length of the game.
Providing the variation that does exist are some nods to Half-Life with puzzles, but all the work that went into the physics engine is pretty much wasted here, because they're boring and almost asinine in simplicity. Place a plank over a gap with a crane to get over it. Clue the user to use the crane after a minute or so, even if he's using the crane, just to make sure he gets it. Duh. Carmack himself said that in a game, if you can't do something well, you shouldn't do it at all. When I did encounter them, I found myself really wishing they hadn't bothered with puzzles.
So is this a great game? Well, yes and no. Amazing, have-to-be-seen graphics. Veteran difficulty is a real challenge. Seriously the scariest game you will ever play, by a wide margin (especially if you play at the appropriate difficulty). You may get tired it before finishing. I'd say there are some problems, but on its strengths, Doom 3 is still quite an achievement.
