Cats enjoy playing but tire easily with the same toy. Offer a variety of toys. Feathery cat teasers, motorized mice and bells hidden in balls are great hits for most cats. Tethered toys are also popular. Avoid strings or yarn. Despite being commonly associated with cats, these long thin playthings can be easily swallowed and result in serious illness. For cats that do not seem to enjoy typical toys, catnip will almost always result in happy playful kitties.
For some suggestions, please read the article Selecting the Right Environmental Enrichment for Your Cat.