Have you played Brainsplatters 2? This reminds me a LOT of that game and it's hard not to directly compare the two (which is kind of crazy considering that game is nearly twice your age.) Anyway...
Virtually everything about the aesthetics of this game are pretty flawed. The drawings, voice acting, writing, and gameplay could all stand to get some major improvements. That said, I have a lot of appreciation for the level of detail put into giving this game every little bell and whistle, even if those bells and whistles are themselves flawed.
For instance, the animated intro, animated menu, and voice acting are all inclusions that aren't strictly necessary for a "click stick figures to shoot them" game, but contribute to a really cinematic experience. In a way, this feels more like a concept sketch or animatic of an actual game, given how lacking the assets are but how complete the structure is.
Aside from the rather generic advice of "put more effort into the graphics" something really critical in making this a better game would be ramping up the difficulty. Forcing the player to click the stick figures faster, making the stick figures move, or more complex methods of killing bad guys (similar to having to find the hiding sticks in the last level) would make this more engaging instead of allowing the player to cruise through the entirety of the game in a single attempt.