Adjustments to think about
Add a duck function.
Add more texture to building.
Ability to adjust mouse sensitivity.
Better coalition detection( sometimes hitting the body and nothing happens to hitting the body and getting a head shot.)
Maybe a story or something I mean I like mindless shooting as the next person but it becomes stale fast.
I don't want to put this down but I'd check out other sniper/assassin games and make your next submission a great one.
maybe add a hitman type theme on the run from cops and to escape you kill this many and fuse elements to make it a full game.
Other then that I see something that can become more.