You can try having a stacking game for the kids with mutli-colored blocks. My son loved that at his party. He also enjoyed the baby boogey contest, where we let them all dance to toddler songs in their own way.
Some ideas for party games that your son and his guest might enjoy are simple games like London Bridge or Bean Bag Toss. Another fun activity is to give the adults at the party bubble solution and wands and have them blow bubbles for the children to catch.
There are many games toddlers can play. On being Pin the tail on the Donkey. With Safety being a big issue, Use a velcro tail instead of an actual pin. Another game could be Hide and go Seek
