T.S.
I love "old school" games and so do/did my kids!
You could do a scavenger hunt (like an Easter egg hunt, just throw candy around the yard and let them find it) pin the tail on the donkey, or a pinata. It's nice to have something "crafty" set up somewhere, even if it's just coloring pages or sidewalk chalk, for the kids who may not feel like playing a game.
Have fun and HAPPY BIRTHDAY!!!