Regardless of how you think they "act" (which is normal for that age group anyway, peak "self" development age right there) you can't do party games with that many anyway. Even if they were older the wait times to play would be crazy unless you did like a dozen games.

I assume about 1/3 of people will no show, even if they are RSVPd

Just do pizza for everyone. Cupcakes so you don't have to cut a cake.

Go to the dollar store. Pick up a bunch of chip and dip trays and set up tables with activities in them. One table have crayons, stickers(so many stickers) paper, makers. Another tray with little plastic animals Tray with lego to build Etc etc

Go to the dollar store and just load up on cheap toys and theme the tables. Like I know I've seen little dolls and funiture, hot wheels cars, even knock off lego all that jazz at dollar tree. I'd say use your stuff but you will run the risk of it getting broken or taken home.

Have some hula hoops, bean bag toss over in a corner.

Let them just play and move around as they will. Play some music in the background.

Tell everyone when they arrive you didn't realize the venue had a earlier cut off time, lie and tell them they'll have to leave after about 90mins. You'll be able to control the chaos for about that long, not more lol.