Great concept, good hook. Not too much explained the in the story or dialogue- which is fantastic- the gameplay itself piques my intrigue as a player.
Gameplay is challenging in exactly the way it needs to be. The music fits. Death is sudden and shocking and infuriating, which, I assume, is exactly what it needs to be. The gunshots are satisfying, I don't think a game with an assassin-theme needs gratuitous gore.
The enemies definitely feel like robots. They look like regular henchmen but shoot like robots with perfect accuracy. I'm not sure how to explain this, but the environment and the enemies don't feel alive. It feels like a simulation (which seems to be the theme of the game?). The music is doing a lot of heavy lifting in creating atmosphere. I think this is your biggest area of opportunity.
My tower sounds like a jumbo jet taking off when running this. Not sure if it's because it's a demo build, but optimization is critical here.
The scoring system is what I think pushes the game into maturity. One small detail and I no longer feel like I'm playing against the game and completing mission- I'm playing against myself. Excellent addition.
Aside from visual polish, optimization, environment... this game feels near complete.