Catherd

Being a catherd (like a shepherd... only y'know, cats...), it is your job to gently herd the cats into the pen.  However, cats being cats they wont just make it easy for you!

Pick them up using your mouse (computer... best not bring any actual rodents here) or finger if on mobile and drop them into the pen, once all the cats are safely rounded up you get to do it all over again!  There are always more cats to herd (probably ones you previously rounded up).  You even get timed so you can make a competition out of it! Now with high scores!!!