I agree that this feels somewhat like an aim trainer. As if the player is shooting these rats with a hitscan cork gun. Instead of whacking them with a mallet.

I think an interesting approach to your idea would be to focus more on creating the feeling of using a mallet to whack these rats. One way that could be done is to have a collision shape be instanced or enabled whenever, and wherever, the player clicks. Then inside the rat's collision handler, it just needs to wait for the mallet collision shape to enter it. Instead of waiting for the cursor to click inside it.

Not only would this feel more like a big ol' mallet striking an area. It would allow the player some more leniency on when and how they can use their only action within the game. The action only occurring when the cursor is clicked inside a rat's collision shape creates an experience that relies more on precise twitch movement and reaction. Where as if the player could just strike some area whenever (or with some cooldown between whacks), that would be more inclusive of varying skill levels. And add some potentially fun and interesting sort of chaos to the gameplay.

I also think increasing the scenarios where a player can use their action(s) can lead to a deeper game naturally. For instance if a player can affect an area with their whack, there is the possibility to try and hit multiple rats at once. There is added risk reward to this. The player could hit multiple normal rats. But now there is the chance to also whack an explosive rat on accident.

Last little game design ramble. A useful way to think about your game is to ask "If there was no goal, would my game still be fun to play?" So essentially, does your game have some aspects of a toy? I feel like my mallet example would help to, somewhat, facilitate this concept. In my imagination I could see a player having some fun, although perhaps just a short few seconds, simply whacking around on the screen. Even more so if there was some "juice" added, in the form of a cool animation, some dust particle effect, a loud thump or thud sound effect, etc.

I hope that ramble comes off as constructive & conversational and not condescending or in anyway negative sounding. The fact that you were able to make a fun lil' polished experience in 72 hours, or less, is awesome. Hindsight is 20/20 after all. After the jam ended, I felt that my game's design could have been more solid from the get go. And I feel the gameplay ended up lacking because of it.

I really liked the art, animations, and overall aesthetic as well. Keep up the good work.