Good level design is not absolute, as it depends on what you like personally. One dangerous aspect of any game design is the dreaded realism-gameplay-axis. Here are some of my thoughts on the subject (I'm trying to restrict my ramblings on FPS level design). Entering ramble mode, please stand by... ... Done.

As far as restricting the player's movement goes, I think Duke Nukem put it rather correctly in Manhattan Project: "Someone is gonna pay for making me find these freaking key cards!", "Coloured key cards suck!", and "Surprise surprise, I need a key card...". I mean, it can be neat once in a while, but I don't find it mentally pleasing to see the levels flooded with arbitrarily coloured key cards hovering half a meter above the ground, revolving around their imaginary axes much unlike the Earth revolves around its own. Having key cards is not the root of all evil per se, but having three differently coloured, yet surprisingly similar key cards in every single level of the game is a frightning thought. Do note, that the term key card is rather abstract here; it can be keys, spells, presses of a button, or what have you — something you have to seek with religious vigor just to pass that one last door, wormhole, portal, whatever. This is just a special case of the real problem, however.

One of the greater problems with restricting the player's movement is the fact that there is only one way of solving such problems, and that solution is defined by the level designer. And the player won't like that. This is what mumpo was saying, I reckon. If there is a puzzle involving a locked wooden door, slowly rotting away in the bottom level of a long-forgotten dungeon, requiring, say, a red, electronic key card, and I just happen to be a gun-wielding maniac with a rocket launcher and a surplus of rockets with me, I really don't see a solution involving running about mazes trying desperately to find a red key card. I see a solution involving an explosion and a lot of splinters. However, most games reward me with a decal on the still quite evidently intact door and an overwhelming WTF-feeling in my mind. Of course, after making such an effort I might not even be able to breathe, let alone gasp in the middle of the WTF-horror, but that is beside the point. The point is to have alternative solutions to problems, but not enforcing a different solution every time.

Don't think like a designer, but rather like a player or like an NPC (after all, it is the NPCs who spend most of their time in these environments, that is, until the player decided to come in to kill everyone). Think how the NPCs would have constructed the environments (regarding artificial environments, that is). Everything in the level should be there for a reason. This is not to say that everything in the level has to have something to do with the player or the story, but with the theme.

Having evident linearity in a level is another major turnoff. This is not dissimilar to the key card problem, as one way to hide the linearity is to use such devices. I'm not saying the player shouldn't be guided in to the right direction (by preventing him to access irrelevant areas), but having every single door not on the relevant path locked (or literally nailed shut, as in Max Payne) shows a lack of imagination. Having the ability to visit rooms that have nothing to do with the story is not frustrating, as long as the player doesn't get lost.

I have to agree with Schultz in the sense that the original Doom levels (and similarly the Duke Nukem 3D levels) were much more fun than the levels in many more modern games. One reason for this was the fact that not only could you play the levels in single player mode, but later play deathmatch in them and see the levels from a completely different point of view.

Reusing bits of the level architecture in other levels is not a sin, in my opinion. In C&C: Renegade, all buildings with the same name (hand of nod etc.) had the same architecture. I considered it rewarding to see familiarities and patterns in the levels; revisiting the same kind of buildings with the same architecture, yet in different situations story-wise, was neat. Even though the general layout of the nod bases differed radically throughout the game, the building blocks were the same for a large part of the game. I don't consider this backtracking, but someone probably would. As such, someone would consider it punishing the player.

(You could even build the levels randomly using such patterns, which could greatly increase the replayability factor (even if it meant just a little variation and not really "totally" random levels). Alas, my instinct suggests to me that Doom 3 is not a formidable candidate for such level creation? Having the levels exactly the same (including the enemies' starting positions etc.) makes the game less appealing for a replay.)

Common structures shouldn't be made labyrinths. After all, real-life buildings are usually desinged to make moving from one place to another easy, not difficult. Having evident sniping points and the like is not necessarily a good thing, as most real-life buildings tend not to have such (by desing, at least). Of course, this is yet another gameplay-realism-argument, so in order to enhance gameplay you might want to throw logic out of the window.

Also, I must admit that I have an obsession of ventilation shafts. The more accessible ventilation shafts a level has, the better. [lol]

While not being all that informative, I hope these more or less flabbergastingly obvious example scenarios are of some help.

Deadpenguin hit the nail squarely on the head, as far as I'm concerned. (Not to mention saving me from typing all that stuff out myself. :P)

Quote:

Interactive objects give the player choices about how to proceed through an area. This generates varied experience, which allows for different players to take a different approach and thus has a different gaming experience.

And THIS is what makes these games replayable. I guess that's my main beef with doom3. There's pretty much only one way to finish it. One set path to follow. So why would i want to do it again? To gun down those monsters with even more superiority? I've played the first games literally hundreds of times, and i can still do something a little different. the third one only once (though i've started replaying it a couple of times. boring). But let's not let this turn into the "why i dislike doom3" thread :P

This might not apply to a DOOM 3 map, but to game/level design in general. It seems to me it's a good idea to let the player feel like a god every once in a while. I mean, you obviously don't want to let them play the whole game in god mode, but maybe they get an item or something that is godlike, but breaks after a few uses. Something like that could really spice up the experience.