I did bit similar one, but only two of my cats got it and most of the others did not even pay much attention, one was just purring and rubbing his head against my knee while kneading the floor, but he did not understood that there was treats, only if I put one into his mouth he understood to eat it and started to rub his head more while purring louder.Well it took me a month, but inspired by @Draco I saved my cardboard rolls and made a super awesome cat toy out of them! Mine is particularly cool because of all the classy duct tape.
They were unsure at first, but Wiggies got into it eventually. It keeps him busy for a while trying to scoop out the treats.
Pushkin pretty much just sits there and watches.
He did have about zero brain activity I think, he was just over happy, but could not understand this toy, even saw others using it.
Those that got the toy did not had interest to that very long, not sure why, they do like those treats but maybe they were just bit tired.
Have to see if there is anything left from toy at the morning.