Wow that makes me sad. Read lots of books, use lots of flashcards, go walking, sliding, I bet he would be great outside with mittens on without too much concern. Ask his parents about their recommendations. Forget about crafts for a couple of weeks. He will adapt his playing in your toy room as you already mentioned. Kids are awesome! How about games like Red Light, Green Light and What Time Is It Mr. Wolf?, Musical Chairs(or mats), dancing, marching in a circle, none of those things need hand movements. Wow, you are awesome apples & bananas to take care of this little boy.