V.W.
Well there is the classic: Look in the paper bag for 30 seconds and pass it... then after it goes around the room, everyone tries to write down the items they saw in the bag. But you might have issues with the younger ones writing down the words adequately for the game.
I have seen a bingo game, where you make the bingo cards with items that the mom-to-be receives... she opens a pair of socks, and if your card has socks on it, you mark it off. 5 in a row is bingo. BUT, if you aren't having gifts for her or don't have a lot of gifts/attendees, not sure how that would turn out. :/
I am stumped. Never really been to a baby shower geared for kids.... Seems like an odd request in a way... (not your question, but the request to help with a "shower" for the kids to attend.)