The game is split into several levels that each have nine scenarios to beat. Each scenario involves a different kind of insect. For instance, in one you'll need to swat 40 flies in 30 seconds; in another you'll need to swat the bees without getting hit by their stingers, all in less than 25 seconds. The gameplay is simple: you control the position of a swatter with the mouse, and when you click, it swats. You must complete every challenge to unlock and advance to the boss scenario for the level, and you can replay them in any order to try for a higher score.
The game is not perfect though, both psychologically and in the gameplay balance. The bee levels in particular really get me, I was stung by 11 bees back in September while walking my dog through a marsh, the feeling still haunts my nightmares; if you've ever had an unpleasant experience with any member of the Arthropoda sub-phylum you'll be able to face those repressed memories here, probably to therapeutic benefit. Then there's the gameplay, because each section is a distinct version of the game, there is a need to give each a deal of balancing and play testing in order to keep the difficulty curve consistent and avoid any nagging issues. A terrible example of this is level 4-1, where you must swat down the fireflies while they're unlit. The problem there is they stay unlit for inconsistent time periods and without warning return to their harmful lit states. There are less dramatic examples of disproportionately difficult sections, particularly later on, that impede the player from enjoying a smooth flow to completion. Topping it all off, the chronic clicking involved in some of these levels can be exhausting, which might just compound with the disgust of dealing with all those bugs, but nobody said the job of an exterminator would be easy.
If you've got the stomach for it, I recommend you suit up and play Pest Control.