Your game was enjoyable and quite well put together, I was surprised at how long I played it for. I love that it was a mix of both puzzle and a shooter. :D
a few notes i made were: I found the enemies a bit difficult to shoot without getting shot in the process as they would all bunch up together and spam shoot me. perhaps giving their speed and movements a bit more variety could have helped witht at.
the other note i had was the big enemy boss, I wasnt sure how to get past that area without dying. I couldnt kill the boss, and if i tried to rush passed and solve the puzzle he would ultimately kill me.
Otherwise I loves the puzzle sections, they really made me think at one or two parts which I quite enjoyed. In terms of theme, I would have lent more into the echoes of nuclear past with perhaps some symbology (the radiation symbols for instance) or clues to the nuclear past present. Overall I am very happy with how much you did for the short time span :)