Pretty good game but i have a few suggestions:
-Ability to continue shooting by holding down the mouse button rather than continuously clicking it would help make the game feel better
-The later waves have so many enemies that by the 11th wave the game just crashed. I suspect you are not using object pooling to spawn in enemies. I suggest you look up object pooling since it will help performance immensely.
-To avoid having to spawn in so many enemies in the first place, try making more variety of enemies that have higher health which spawn in later waves.
-Some kind of text that conveys what each upgrade does. Since all the waves come in continuously you don't have time to parse in what the icons might refer to.
-A more indepth explanation of the hope mechanic in the game, or atleast in the game's description.
Hope you the best of luck.