Being an indoor cat, he must be totally freaked to find himself outside all night after such a terrible adventure
Sure hope you find him
I have a friend who has had all her indoor cats trained to be outside on a leash in their fenced back yards. The cats are safe, but can still enjoy the wonders of the outdoors and not get into too much trouble. Not sure how a 10 year old cat would catch onto the harness and leash idea, but it may be worth a try.