My two pennies:
Half Life 2: Yes, it has graphics, yes it has physics. Sound? Forget it, the sound is terrible, very little in the way of music and when there is some it's not at all appropriate. Some sounds have been taken DIRECTLY from Half Life 1 (the Magnum, for example and the Vortigon's energy sounds like the Gauss Gun powering up) the pistol only has a slight 'click' for a reload sound.
So sure, Half life 2 promises a good game but it doesn't really deliver, I played through with some hope of a storyline to make itself known, I was dissapointed though. Realism is virtually non-existent, it suffers from the same problem as Half Life 1, a HEAD SHOT IS INSTANT KILL AND BULLETS ARE NOT BLOCKED BY CLOTH! Seriously, it takes two, yes TWO, pistol bullets to the HEAD to kill a guard wearing nothing but a cloth over their head, realism please? Not to mention the fact that a SCIENTIST shouldn't be able to use military grade weapons with pin-point precision.
Physics, alright so it is pretty good that weight is brought into the game, but please, a few more DIFFICULT puzzles would be nice, instead of piling up bricks to get somewhere.
Overall, Half Life 2 promised so much but delivered so little.
Doom 3: Now this game... this game... scares me. This has awesome graphics, and like someone previously said, the dark is part of the atmos, this is actually the SINGLE game I have seen that comes with a health warning inside. It says that those with a heart condition should NOT play it, to enjoy it at its best, turn off the lights, lock the doors, turn up the sound and enjoy...
I would bring this up on the realism factor but for the fact that it never claimed to be realistic in the sense of headshots killing, you're blasting at zombies and hell-spawned demons here, they're not going to go down as simply as a human being.
The sound adds to it all, every small sound got me shaking and looking over my shoulder to check nothing was there, a door opens without me being near it, I jump so much that I empty my machine gun clip at nothing.
Now, the flashlight slightly annoyed me with the marine not being able to hold it at the same time as his sidearm or attaching it to his gun, but that isn't enough to put the game down, its more a situation of see it but can't shoot it or shoot it but can't see it.
Overall, Doom 3 scares me to this very day, and the TC they're making only makes it even better, which will re-do the original DOOM levels with the D3 engine, can't wait. :D