I've always loved FPS games. I like the counting mechanism for the battery. The visual is good. Overall the thing that don't really fits is the bgm. IMO maybe something more suspense would do!
Also, this game has the potential of fast pacing shooter. So maybe a little bit more mechanism like sliding will make the gameplay more fun. And I do recommend you to make jump buffer method too, so the movement will be more flawless.
Good one, and goodluck with your submission ;)