Personally, if you are over 29...scrap the idea of games. They are too childish in my opinion. What reunion year is it? I just had my 40th h.s. reunion, but that's a whole other story, as my school was all girls (at that time), and all years are combined in an afternoon tea (boring).
People will provide their own entertainment...catching up with each other.
A few ideas I do have:
1) Have a bulletin board and post pictures of folks from when they were in high school, but do not label who the picture is of. People like to guess what people look like now as opposed to back then. (Ask people to send them to you beforehand and return them at the end of the night).
2) Did you have a prom? If so, you could make this your theme. Have the deejay play music from the years you were in school. Decorate the room the same as the prom was decorated. You could even elect a prom king & queen at the reunion.
3) Put disposable cameras (do they still make them...I'm showing my age!) on each table and let folks be their own photographers. (Yes there is developing cost here.) Post pictures of your reunion on Facebook or a website. These can be put on a bulletin board at your next reunion.
Hope this helps. Enjoy yourself and have fun!
Anita