Most of our cats lived indoors, all but one lived well past 16, one went 21 years. Fed 'em Purina cat foods, open-feeding for the dry kibble, canned Friskies fed twice a day. We now feed three that were abandoned about five years ago, family left their house to foreclosure, the cats with it. We couldn't see letting them range around, as they'd been raised from kittens, being fed by and dependent on humans. We now have "Occasional Cats" Lucy (orange tabby), Fred (all black, short-hair) and Ethel (looks like a miniature Maine Coon). Raised outdoors, they don't particularly like being inside but will come in, in the morning for breakfast, eat some canned food and Fred and Ethel will usually want to return outdoors. Lucy will head for the bedroom to curl up on the bed and sleep off the night's adventures. She's the most indoor friendly of the three. We estimate them to be about 12~14 years old now. As "winter" here gets colder they are more inclined to appreciate indoor comfort, finding various spots to spend hours napping. Fred's the most docile, purrs instantly with a hand petting him. Ethel has learned to "sit" for a treat, the other two wait for theirs until she has performed the trick and then get theirs for "free".
Many years ago a friend, knowing how we care for our pets, told me that if he were to die and be reincarnated, he'd want to come back as one of my cats...