Woah, that's a lot of feedback. I'm glad you're finding the game more fun after trying it again. I did end up recording the video you requested, you posted your new replies while it was rendering/uploading. I don't think you need it anymore, but here it is regardless. It has some commentary to help explain what's going on.
I found a (software) bug:
The link is dead, could you reupload the file or describe the bug?
Does using the plasma on the blast explosion enemy cause reflection and harming the player? While using it on the gas explosion enemy insta-kills that enemy?
Plasma causes lightning arc on any hit enemy, it just builds up faster on robot enemies (all enemies currently in the game.)
I have not yet been able to reliably visually differentiate the two types of exploding enemies, especially in darkness, but I might figure that out eventually. The color of their "eye"? Red for blast explosion enemy, yellow for gas explosion enemy?
Yes, red is explosive and yellow is poisonous.
What are the differences between the floors? I do not know if I have found any difference between floor 1, 2 and 3 so far.
None thus far, the latter two floors are there to just extend the length of the demo a bit. You could clear a floor in 1-2 minutes even on harder difficulties.
How do I pause the game during combat?
Pausing is not implemented yet.