There are many games to play with little to no prep. but you need to be OK with facilitating them. Four corners is always a hit and quiet. 7-up is great (especially at the beginning of the year when kids are learning each
others names)too. I instruct my five tables very explicitly on how to play/handle five activities. They are: homemade playdough with cookie cutters/plasticware, legos, a shape perceptual card activity, construction straws, and pattern rings with shoelaces for stringing. Often times the children play at tables and we rotate them as needed. I even do this so I can quick do a reading
group immediatly when the kids first come in. I'll teach the children how to play a new game/or activity changing only one at a time before I do another total rotation. I call this time, table activity time. It's working well for me. Rules for playing together also need to be in place/modeled so they can handle differences if they come up. Hope this helps.