What is a fun bonding game/ activity for a Step Mom and 5 year old?

I have been dating this WONDERFUL man for almost two years now. Awhile before we started dating he had broken up with his wife. He has a wonderful 5 year old boy named Gideon. We used to be best friends... but six months ago he moved with his mom to the next state over. His mother doesn't like me because she sees me as "The other woman." Which I'm not, we didn't even go on a date until long after they were over... But anyway since Gideon moved to Oregon he has had nothing but "Dana Influence" (his mother). Now he is back visiting for Christmas... I know deep down he WANTS to be my friend (that's all I want... I'm not trying to be his mother)... but he's told me several times that his mommy doesn't like me. He is acting weird to me... stand offish... and even angry sometimes... which isn't like him. Does anyone have any good bonding ideas that I can do with him while he's here? I would greatly appriciate it. Oh and... keep in mind.. I'm broke after giving him his Christmas... Thanks!!