Tech Demo - Far scarier atmosphere, mainly due to the fact that the rooms were smaller (claustrophobic). Also, there weren't any patroling enemies so you a bit jumpy at times. It waxs far more super-natural than Black Plauge or Overture.
They planned the Tech Demo to be much longer, but they had to shorten it to get it into a game competition.
Fun Fact: When going through the files of the Tech Demo, they have alot of un-used concept textures. Bathrooms, kitchens, sofas, texture for dead body, guts, and so on. No extra models though..
Overture would have to be next. But, alot of the scare factor was removed due to too many enemies, and predictable level layouts. Also, the tunnels were too big/too symmetrical.
If they were smaller, sometimes headed in a different direction (maybe sometimes upwards), and had more detail they would have bee much, much better.
I'm rating black plague as the lowest. I had several problems with the game;
-Too Dark
-Disappointment in using same level-type designs as Overture
-Technical difficulties (still unresolved, thanks frictional for moving my topic to modifications!)
-Too few enemies
The storyline and Clarence idea were great. But Clarence's 'humor' brought him down greatly, also his large speaking abilities.
The environments were boring. Very, very boring. Oh look, another hallway. Oh look, another room with a chair in it. Oh how fun!
The levels I thought were often too dark, even an occasional light would spruce it up.
I didn't feel entrapped like I did in Overture. This was because things were alot more modern and 'people' like. Also, you were very close to the surface.
Finally, my biggest gripe with the game. You found your father too fast!!
Fun Fact: I think that finding your father was the end of Episode 2, when they thought that they were still doing episode 3.
So; Tech Demo>Overture>Black Plague