I think the best way to get people involved is to walk around and visit with them personally, thank them for coming, introduce them to people they might not have met yet and just generally spend time with your guests. No games are necessary to accomplish this.
If you dont have time to personally visit with each guest, at least in small groups, then you should consider cutting back the guest list a bit.
I had 4 showers (yikes, I know) and didn't play a game at a single one of them. All 4 latest 2-4 hours each and were perfect. I visited with everyone. We laughed and shared funny stories about how we all met, life with kids, pregnancy, etc. We had good food. I opened presents. We at cake and visited some more and then everyone started heading home. A good time was had by all.