For it being your first game, I am very surprised on the scale of environment that was developed. Usually the environment is about as big as a 1 - 2 bedroom apartment, so kudos on that. The cinematics and soundscape were pretty good, but the opening sequence was a bit laggy. My suggestion for the development of your next game is: try to focus on bringing more details (info & visuals) to the game, like individual backstory, npc, more dialogue. I say visual details because the environments felt hollowish, like more should be seen in certain areas. The little details are very important for immersion!
Great work!