How old are your children? It is difficult for kids to understand why kitten hides and why they can't force him to play.
I would keep Ozzie in isolation, in a room, preferably without a bed or dresser to hide under. But do give him a 'safe place' to hide that you have easy access. A tupperware bin with a door cut into it works well. Put a soft blankie in it for him.

Right now, he doesn't trust anyone. It would be ideal if he only had contact with one person, for a couple weeks. Then you can gain his trust. IF he still won't come out, when you are the only person with him and the environment is quiet, slowly pick him up, while sitting on the floor (not standing up) and cuddle him against you chest for a few minutes. Use a wand toy for play, it keeps your body away from him, in case he is very scared.

Above all, make sure he is eating. Don't let 24 hrs go by without him eating.

PM me if you have any questions.

(I foster lots of kittens, and work with the scared ones)

He can and will change! But your children will have to learn a great lesson in patience!