Hmm, Honestly, I guess my trick of "Repetition"
Because If you were to listen closely, it is the same melody, chords, and instruments, I simply added variety to not make it boring.
I do this with my other songs too.

Also, if you were to listen to all my music, you would see that most of them are long, about 3 to 5 or even 7+ minutes, I been making long songs since I started producing music.

I personally like the repetitiveness of music, think of it as a "Trance"-like feeling.
I do add some variety so that it doesn't sound boring, and for this one, I tried to consistently have that, sort of "Melancholic" sound throughout, and since it is a journey, I made the entire song an odyssey.

That probably didn't make sense, I'm sorry if it doesn't, It's really hard for me to explain what I do in my songs, Which is why I simplify my genre to: "experimental" since, I don't know any other word to explain what I do with my works LOL.

But Anyways, Glad you like it!
And. . .yeah, I hope I didn't waste your time with this long paragraph xD. Have a great one!