I really liked the game.
Tried to force them go my way but it keeps finding a better path :)
You can try to add some bg graphics, music and sfx and game will definitely look better that way!
Good job!
Viewing post in CMY Tower Defense jam comments
Ideally you would have a team mate who will take care of that.
But the easiest way is to get some free sfx and music.
You can check itch.io there is an assets section for that.
If you want to try to make your own music and you don't have any experience playing some instrument (e.g. piano, guitar) I would recommend something like fruity loops (FL studio) where you can combine existing patches to create something new.
Or if you are able to write music on your own anything like cubase, ableton and etc will do (with different sample libraries)
Good luck with that!