Very nice game! At first swatting the flies felt unresponsive, it was hard to gauge the hitbox I guess but I think I got used to it well enough so, it works out decently I think. All the game needs is a bit of polish to some graphics (although it's pretty artistically consistent which is great - I pretty much just think the swatter needs a tweak). And you clearly know how to use shake and particles for feedback, so I'd say just do more and more with that (not to overdo it of course). Good stuff.