It's a fun idea, but alas, it does not seem to fit the theme in a really apparent way. The first time I played I thought it was a game about only getting one slime per sweep, as to do otherwise would subtract from your score and cause you to potentially run out of slimes.
Soon I realised this was not actually the case, so I tried to aim for single slimes in order to accumulate a bunch and then sweep them all in large quantities. It was... a mild success. As it happens, simply spam clicking near the edges ends up producing better scores because of loose slimes caught there raising the number of slimes overall, and the sheer speed of spam clicking just sweeps more slimes than my aim and calculation ever could.
So the idea is fun, but the exact rules, balance, or mechanics should be rethought or redone in order to better fit the theme or present more of a game for the player.