The only shower game we played was making the guys drink beer out of a baby bottle to see who could finish first! We only put 4 ounces in, but it is HARD! The winner got a cookbook for wings/burgers/beer recipes.
Possible centerpiece idea. Tie balloons to current vases Balloon Centerpiece using mason jars.like this idea you can fill the jars with whatever you like - Candy for kids, shells, colored marbles, flowers, themed items. A Good idea to shelf.
Games - Bottle Chugging I don't know if this is the crowd for this, but sounds fun to me. Fill baby bottles with your drink of choice. Make it a bit more fun for non-pregnant guests by adding some booze, then have guests race to chug them down.