You’re having 10-15 four and five year olds over your house for a “party.”
First, have a set time. Three hours seems to be optimal.
Second, you can do games if you want, but I don’t like to at this age. Think about it. It involves gathering a large group of rowdy kids you don’t know that well and shouting instructions at them, hoping they’ll coalescence into a cohesive unit of teamwork. Totally reasonable to expect that of this age group, right?
Instead, I have random distractions planned. They came in, there was a bounce house. When they started to tire of that, I put out the snacks, when they had eaten and were just getting bored I hid some bubble containers around the yard and had them find them and blow bubbles, all while I was ordering the pizza.
The pizza took longer than I thought, so we lined up and did the pinata while we waited and I got the cake ready. Then, just as everyone was losing steam again, the pizza came. Then cake, then presents and oh look the three hours is up. Goodbye.
Also, make sure to invite friends of yours too. Have adult beverages and enough adults so that they can talk to one another as the kids play. Let the parents drop their kids off if they want, but create the kind of atmosphere where if they stay, it’s not all about wrangling the kids from one activity to another. It’s actually about having a good time at any age.
In related news, I survived the party yesterday.