Thanks a lot for your comment !
When seeing the image theme, it gave me a bleak and cold vibe based on the main colors (red & black with a white highlight in the middle of it), so I went for a depressing dystopian future ruled by an authoritatian force (inspired by the stories of 2112 by Rush or Stray for the dome part), with the music using a mix of electronical instruments and guitares/basses to reflect the tense and cold vibe of the story.
I really liked writing En Force (certainly the one that took me the most time because of the guitar recordings and the complexe structure), so I'm glad that you liked it too ! The synth note was also indeed meant for an alarm kind of sound to make the tension constant.
Once again thanks for listening (and for taking the time to take a look at my illustrations and the story on the project's page, it means a lot) !