Personally I LOVE games and have a lot of ideas but probably nothing really exciting. I would go with some simple things: Price is Right, Guess how many Q-tips are in the baby bottle, 15 items on a tray carried around by the MTB (if she is able) and then once she leaves you ask questions about the MTB (what color of pants/dress was she wearing, shoes, earrings, how many, necklace, etc, etc). You just tell guests to make sure they have a good memory. They, of course, are surprised they have to give answers to questions about the MTB since they were concentrating on the tray. Easy ones are "baby" word scrmble or to get them thinking...finishing off nursery rhymes.
Another fun activity is to use fabric markers (wouldn't use paint since it takes forever to dry) and have guests decorate bibs. It is kind of costly compared to other games.
I'm not fond of the candy bar melted in a diaper or smelling baby food in a jar or chugging applejuice from a bottle. I've done them...but not fond of them. Baby bingo is a good game to play during the gift opening segment of the shower.
BTW...I don't consider it childish or immature to "play" games at a baby shower. It is tradition and I'm all for tradition. It is also fun...especially for the person that doesn't know the people there and socializing is at a minimum. Course that is my opinion.