If you've played Daydreamer, you'd know that the game's premise relies on entering doors and experiencing different dream-sequences. Currently the game only has 3 such sequences, but I've began working on a fourth!
Here's a sneak peek at what it looks like:

I feel like this is the most "horror-y" sequence yet. It has a creepy and foreboding atmosphere. It reminds me of the feeling of exploring some abandoned and dilapidated concrete monster, full of grime and god-knows what.