Thanks for the feedback!
The music and sound effects I will definitely change either in the next update or the one after that - I'm just trying to figure out either where to find appropriate music/sfx or how to make it. With models, I am going to replace them in the future, starting with the watch tower in the next one, and patrol robots and the player after. I'm no expert in rigging and animations though, so I'll have to work on that before I make the player model (the patrol robot might not need too much animation as it is a robot, so I could design it to not be humanoid).
Thanks especially for the feedback about throwing the projectile - When making the game, I wasn't sure how I wanted to throw the projectile as using the mouse was more intuitive, but meant that the game couldn't be played with the keyboard alone, but as you said using the current system can be difficult to know where it will go. I was considering was making it an option to use either space (current), IJKL or the mouse for throwing the projectile so that the player has more options and it can still be played with only the keyboard. If you have any opinions or suggestions on this idea they are very welcome :)
(I'm also a beginner developer so any advice is helpful :) )