My overall Opinion: Excellent Start, but I recommend the creators take a second pass on it later when you are ready to update it. :)

To begin with, I have NEVER made any video game before, much less in 3 hours.  I think WatchTower is an excellent start, with some improvements to be considered, so take my opinion with that understanding.  I am impress you made this within 3 hours and that is commendable.

I love the music, and the artwork is fantastic.  I feel like I'm back in summer 1994 with my best friend and I staying up late on a Friday Night playing our Super Nintendo.  So thank you for the trip down memory lane, Watchtower creators!  

My suggestions to improve: 1.) Perhaps an explanation of the main controls before you play would be helpful (I died a few times not know which keys to to push and had to ask one of the creators what controls to push).  To play, press the SPACEBAR and the UP, DOWN, LEFT, and RIGHT on the keyboard.  Also, a button to replay after dying would be good.  You have to reopen the game to replay, which is inconvenient.

2.) When the enemies come at you, it is a repeating pattern that easy to track, and just keep following the same pattern.  I was able to see it and keep pushing one button and beating all the enemies.  It got repetitive and when I was done, I let myself die so I could move on.  I did kept playing because I liked listening to the music, but I stopped when the BG Music stopped playing.

Those are my thoughts and suggestions if the creators want to make improvements to a game that has a solid start.

All the best!