The game looks really nice, and I love the environment. The giant squids attacking you, the eerie nature of the artifact and the whole atmosphere were excellent.
But for the life of me, I have no idea what the heck you're supposed to do to beat it. I tried shooting the monster with flares, I tried to search the area around the artifact, I tried to return to the start and report in, nothing seemed to work.
As fun as it was, I do also think the controls should probably be revamped. This felt more like a sort of fighter plane than an underwater submarine.
Still, I had fun! Creepy atmosphere, good cutscene, a nice bit of world building. I'd be happy to see more of this game world, learn more about the War of Fallen Angels and the aftermath. Keep up the good work!
2nd Part of the video here (~5 mins in)