Agh, I planned a BBQ house party today for my graduation and now it supposed to rain!?

As of yesterday, it wasn't supposed to rain for my party.But now, my graduation party begins at 4pm and it's supposed to start raining at 4pm and be chilly now. I had plans for the party to be in my backyard and use my house as well, which I would have croquet and washers. But not that it's raining I have no good plans for my guest. Do you have any quick ideas to spice up an indoor party? I think I'm going to have about 30 guest.