Yeah C-2 is really hard! I could have handle better the difficulty ramp in that area.. Sorry about that.
C-8 is a bonus room, these are significantly harder :) I suggest you ignore the card and focus on reaching the next room first. Once you reach B8, you can focus on the card in C8 then (and you should respawn from the top).
The red cube is the ultimate challenge of the game. It’s like a permadeath mode.
For the npc dialogs, these are revealed by collecting the memory cards.
Thank you for your feedback, I’m glad you finished the main rooms despite the difficulty.