It's simple, it's cute and it's fun! I feel like it could be a nice addition to increase the suction power as you collect more slimes so you feel like you're getting better at it the more you do. Also some visual representation of the vacuum - a cursor shaped like a vacuum cleaner could do it.
Although it's very simple, I do think this is a game that could be expanded to become more addictive, in the same way that survivors games are simple but addictive.
Nice job. Keep it up.