The 4th song is probably the darkest of them all, but I prefer the more modal songs. The melodies are easier to remember, when they're less chromatic. There are some nice parts in the 4th song too though. The part at 1:27 stands out. Really slow and gloomy. Sounds like doom metal to me (I don't listen to doom though so that might be way off).
That part (in song 4) has secret in the drums, it mimics sea waves crashing into rocks and flushing across the sand. For me the part starting 2:14 is creepy and atmospheric (and doomy), I fucking love it, very simple yet genious, it's like you can smell the putrid algae / rotting seaweed and sense the presence of an unseen danger lurking about. It really is a doom song in spirit (much more than black metal). The tritone thing closer to the end of the song, with that bass octave thing, is also quite moody. The intro I love too, it's short but sets the mood perfectly, also the outro. There isn't any material I dislike, if there was then I'd thrown it away.
Interesting song. It's a bit different stylistically than the others I think, but that's not a bad thing, variety is good so long as it's not a complete turn over which this is not. Probably the least gloomy song so far. One of the better drum arrangements too I think. One of my favorites alongside songs #2 and #5.
Favorite part of the song is the melody starting at 2:06
This song feels like doom / black fusion. That part you refer to is the refrain / chorus. You'd be surprised how it's played, it's quite weird, there's dissonance and a sweet melody both occurring to accompany the bass thing. I like how that bass covers the low and high register and has both dissonance and melody in it.
Then of course song 5 is stylistically in no sub-genre of metal at all. It's more about the spirit being identical, with no strict boundaries set by style. Out of all the bands I listen to I can feel unconscious influences from each of them, but it's all coming from within and I don't think there's any band that's similar.
It's a theme album with songs giving different aspects to complete the story - just like in a song you have different sections to form a complete story. I start an album by thinking what subjects / difficult emotions / memories I have to deal with, then find a symbolism for them, and they become song ideas. Then figure what is the common theme the songs share, so I understand what the album is about. Having ideas of songs before thinking about music (both the symbolic form and psychological form) helps me to separate musical ideas as each of the songs have a different vibe.
The next album will be far different in style and I've had a vision about it for quite a while. One thing I learned is I will make sure I have enough time to dive into a song, to come up with the foundation ideas on the same evening, this will make it much faster and less painful to put a song together. It will need to be more fluent.