Recently we brought one of our fosters back to be fostered again for a little while so that her daddy can move and get their new place ready. This cat is only a year old and gets bored very quickly, she is also a little shy around our cats and was slowly introduced but still has some anxiety around her Mama (who doesn't remember her).
I bought a toy that I thought would be fun for all three cats and keep them engaged and occupied for a little while.
This toy was a total bomb in my house and with my friend's 5 cats. It moves too fast and makes too much noise. the cats were afraid of it. I moved on to a floppy fish.
While this was not scary it did not interest or captivate our cats at all. The cats in the other house like this toy, but our foster has no interest.
I tried one more toy and it seems to be a hit. All three cats like it and it is very durable.
Our recommendation is the ORSDA 2-in-1 Interactive Cat Toys for Indoor Cats. It comes with plenty of refills and an extra ball. The batteries are not included.