Considering our furry friends are in their cages 80%+ of the day they need to be provided with a lot of stimulation and play activities. These can be wooden toys, chew and tunnels, or plastic, or even cardboard, just as long as they have something.
The main thing is obviously wheels, which I have covered before, and then there are a variety of other stimulating toys you can provide them with. Currently, Munchkin has a puzzle hanging from the top of his cage with almonds in and he has to work it out to get the sweet treat. They all have wheels and loads of cardboard toilet roll tubes, houses, bridges, tunnels and more. It can also be a great way to fill your spare time by making your own hamster play things.