It may sound obvious but things in a game must have recognizable form and function. That bright thing on the wall has a shape resembling a button, but it's just a light. In other levels the same light is used and with a different color.

The object with the green light doesn't do anything in the game. It has no function at all. Even its light isn't bright enough to light the room. What is that thing? It's impossible to tell what that thing is.

This huge shaft is filled with harmful plasma and the player has to turn the plasma off to progress. Can you tell what that thing is? A warp drive from Star Trek? A nuclear reactor? A shaft for energy beams for the Deathstar's superweapon? The whole game suffers from having non recognizable structures, weapons and an overall abstract architecture with no meaningful purpose. An alien world isn't the same as a world where nothing makes sense.

This place also depicts another error in the game, a failure to be coherent with its own rules. How can the spirit of the player be immune to fire, pass through forcefields but at the same time die to falling from heights and be vulnerable to weapon's fire?

This door has a shaft above with fire coming out. The level's name is about following the fire "Guiding Fires". Yes, the player does follow the fire. However, what is that fire doing above the door? What is that ventilation shaft doing there? It doesn't make sense. Somebody placed those there without caring about what the architecture conveys to the player. It's counter-intuitive as the fire placed there conveys the idea that behind the door there is some hazard related to gas or fire but that's not the player finds upon going through the door.

The player goes through a room with a panel which reads "Shuttle transport system". After activating a control panel that blue ring shows up. Does that look like a transport system? The player has to guess that it is to progress to the next area. The game lacks coherence with the transport system because some parts of the alien mega structure require the ship to be transported by that blue ring while others don't. There is no coherence in this game. It feels that each level was made to present the player some challenge of its own with no cohesive theme being developed.

The health recovering objects in this game doesn't look like anything that the player can relate to. They have a form that is completely unrelated to recovering health. The weapons also suffer from the same problem, their design isn't intuitive and the player can't easily recognize its function or purpose. Not only weapons, the whole game suffers from non recognizable function of devices. Being alien isn't an excuse to make objects that you are unable to recognize.

Level 9. The game makes a gross mistake here. The landing pad is not highlighted while at the same time there is a blue light that is nothing but a pretty blue light glow. The game lacks coherence in its architectural choices because the same thing that has a blue glow here has no light at all in other places.

Imperial city mission. The end of this corridor looks like a dead end. But it's a lift and the player has to go there to progress. The lifts in this level don't look like lifts. Now before going on to bash the developers I'd take a step back and say that the design decisions made at the time may had had different philosophies driving their motives. In doom for example lifts could look like innocent corridors because they were designed to be traps and that isn't a mistake. What confuses the player is the fact that lifts which are the important path to follow end up being hidden by not looking like lifts. It's counter-intuitive.

It's easy to recognize the shape of these computers in DNF. The problem are the textures. They made it feel a bizarre combination of cash register and automatic telling machines. If you look at the buttons, screens and panels it all looks randomly drawn. The direction of this game was really bad.

The Hive. Inside this alien's structure there are organic doors that require a key to be opened. The key is a creature that is round and emits purple light. For some reason the player cannot grab the key. He or she has to push it, rolling it over great distances to open the door. It's a bad design decision because it adds complexity to the game for no reason.