The atmosphere alone makes you forget all the lacks and shortcomings Doom 3 brings.
We can forget the lackluster scenario of how a single man can overwhelm the entire demonic horde without the help of anybody. It worked well in Doom 2, because the game did had any story, but when the story is well developed in Doom 3, it feels strange that the gameplay formula did not change from the previous games. It's like Doom 3 tries to be both - as much realistic as possible with it's great graphics and well executed character story telling, and at the same time not realistic at all in a sense, that you alone manage to survive knowing how many marines and ordinary men were in the Mars base, when the demonic invasion begun. If you can forget this mis-concept, you will find Doom 3 to be an old school "run and gun" game, well cross-linked with the many cut scenes, dialogs and text notes in it. I personally have found this mix awesome, because at times i was getting tired of the same linear non stop shooting and wanted some background details on why i am where i am. So like said - gameplay will feature many game engine based cut scenes, dialogs between the personnel of the base, and many many notes and memories from the people - all that is just to suck you into the game, and keep you wanting for more. And it sure works great!!! Doom 3 definitely takes a long piece of time before the real action starts. You will spend alot of time by just exploring the base, talking to personnel, and getting into the story of how is life in Mars - all this creates an unforgettable atmosphere, that makes Doom 3 one of the most memorable games of all time. After this intro with what is going on, the action starts and develops into a meat grinder fast enough. You will travel through some 26 levels, packed up with all the classic iD guns, those do not need introduction, combating well known monsters from older games as well as new ones. The killing action won't last forever, and after some time you will enter the moments in the game, where you will be filled with new objectives, meet people and talk to them, or find and listen to personal data files. There are lots of PDA files scattered all over the place telling you about the horrible experiences of men, ways of solving puzzles, or showing keys for accessing store rooms and lockers, where you can find additional power-ups or premature weapons. PDA is an awesome gamplay experience, without it Doom 3 would feel certainly more bare...
Technical design, concerning sound and visuals, is of course astonishing, although i could argue from the graphic point of view, that only shadows and model detail look ultra realistic. What i criticize in Doom 3 graphics, that it does not have large, wide open spaces with different textures to fully show the capabilities of the engine - with that said, all of the Doom 3 levels and their textures look kinda the same, there is not much variety in texture pattern, almost as if all of the 26 levels were shaped from the same metallic substance, and that certainly does not make Doom 3 the best looking game of 2004 - it is overrated as it certainly lacks those rich textures Half-Life 2 or Painkiller have. It is amazing how many people miss this part.
The levels themselves in terms of design and atmosphere remind much of what Quake 2 offered - although the levels in Quake 2 were more versatile and once you realize that Quake 2, generally, is alot faster game than Doom 3, it is clear, that you can get frustrated in Doom 3 at points, where you are surrounded by monsters or where you don't see any shortcuts to execute.. With that said, Doom 3, still being a classic old school "run and gun" shooter, is not a "fast paced" shooter like Quake or Painkiller - you just don't get that much of freedom. What is more to it - the feeling of freedom will diminish even more, once you will notice how dark it is in all of the 26 levels - that is the part of the great horrific atmosphere, but unfortunately your only source of light is a 20 century, battery-based legacy flashlighter, which can not be used together with weapons at the same time - sounds totally unrealistic in the game, that takes place in 22 century... The story, as you know, develops in Mars, and as such there will be times when you will have to go to the surface of the planet.. Now you get to wear a mask that will support you with oxygen for some 30 seconds and then you will have to find another tank of oxygen for another 30 seconds - wow, those tanks must be really already used-up, since one would think that a fully loaded tank could provide oxygen for an hour.. The low gravity of the Mars is not shown and we see objects move with the velocity just like in earth. We can also speculate that the protagonist of the game can take the low pressure of Mars without any adaption first or getting dizzy first. Another most unrealistic thing is - if you fall down from the height of some 2 meters, then you die.. How stupid is that? At points it's very irritating, especially considering that Doom 3 is a fantasy game, where you carry tons of weapons, heal yourself with med packs and can do a rocket jump. Also the fact that you can kill any demon with your flashlighter is almost hard to chew, but even that is ok when compared to the way monsters die in Doom 3 - they all turn to ash! Turning to ash would make sense if a monster had been killed with a plasma gun or BFG, but this is the case with all weapons on all monsters - Doom 3 really needs a mod, that would enable gibs and chunks instead of ash.. With that said, Doom 3 also really needs a mod, that enables a fixed light source either on the weapons, or on your armor.. It would also benefit from the fact if you could kick weaker monsters off from you with a leg, but in general the fights look good, because the monsters are amazingly well animated and sound so damn good! Don't expect much from the AI though. The variety of monsters is very pleasing - almost all of the Doom 2 monsters are present in Doom 3 too, with additional ones, and the final boss is a really huge piece of meat.
I won't comment on the mutliplayer, because it is included just "by the way". Doom 3 is just not a game made for competitive multiplayer action.
In the end it is safe to say, that Doom 3, with all that anticipation, was too ambitious for what it delivered and suffered from some unpolished things..
With all these shortcomings however, Doom 3 is still a great great game, simply because it delivers such an unforgettable atmosphere through the gameplay - how can you not creep out when a fat zombie suddenly attacks you inside a toilet room or when a screaming demon head pops out from the shoulders of a woman...