After buying a $5 cat toy and having the cat completely ignore it, and another electronic mouse and having the cat terrified of it, I think the best toys are free.
My cats favorite toy is a stick. I can spin in circles and my cat will be delighted to chase it around me over and over again. It also likes aluminum foil balls, though it's favorite is ping pong balls. It loves batting them around and chasing them.
Strings are also the universal prey of cats.
Floss is a bad idea, although it's cute to see a cat try to swallow it, since they awkwardly have to twitch their head and suck it in, it doesnt get digested sometimes because of wax coating and strings off their butt. We had the unfortunate time of this happening because the kitty, after using the litter box, with half the floss still inside, and the other half dangling with kitty poop, decided to chase the foreign string that seemed to be moving every time she turned around.
I found elastic strings are best. Dunno what it's really called but it's rubbery and came with some christmas gift. They seem to love attacking things as you move it around a corner or a tree.
A fun interactive thing to do with the cat is hunt grass hoppers, specifically the ones that fly. They come out when there's a lot of sunlight. My cat loves to pounce on them and eat them, but sometimes she spazzes out with the tunnel vision and loses them. It's fun calling her when I found one and watching her go into kitty kill mode with full excitement in her eyes. If you think this is cruel don't mow your lawn.
This evening I'll try paper air planes and see how it goes. It's scared of Frisbees, tennis balls, and soccer balls. It would be nice to have sometimes it can chase when there's no grass hoppers. Buying an electronic car seems like overkill for the cat, but could be fun. Maybe one day.
Coloring a favorite toy is useful because cats can see purple, blue, green and yellow. A blue or green string would be much easier to follow than a red string. It may seem weird to think "limited color vision" but even in humans we have limited color vision. We see only a very small part of the light spectrum, which we call the visible spectrum. Maybe cats see a higher frequency that we can't see? Who knows.
I don't believe cats are really lazy. I think they become that way. Stick a human in a room every day without anything to do and watch what they do. Their brain rots away as they sleep more and more, with reality only being a frustration. I think cats really need a LOT of exercise to keep mentally healthy, especially poor kittens.
The sad truth is that many cat owners take them as low maintenance animals which they do not have to walk or really interact much with. I've heard they sleep 80% of the day. I think this may be true for indoor cats, but outdoor cats are not quite so lazy. It doesnt take a whole lot to make them exercise. Cut their nails and spin around in circles with a string. They cover much more running area, and it's fun to get dizzy.
If you're thinking about spinning your cat in circles instead, I've tried it, my friend has too. They *can* get dizzy, but it takes a lot more than what you can stand.
Use the couch, a pillow, and a blanket to make a small fort/cave. The kitty will be immediately interested. All I have to do is peek inside it from the kitty to fly in their to start pawing/clawing me through the small opening.
If you have a treadmill put a line of white tape on it. It will immediately be interested in trying to kill it.
Stick a piece of tape on the kitty's tail. It goes crazy trying to run away from it.
=/ mine doesnt respond to mirrors
Rubber bands are a kitty's best friend, they're easy to fling and cheap to buy.
Use a heating pad. Cats sleep on the TV, under cars, or by the window because it's warm. A good heating pad in winter is kitty bliss.