I have an iPad and my son plays his games on it.
We are getting him his own iPad.
How can I transfer his games over to his iPad with out giving him the same Apple ID as mine?
You can create an Apple ID for him when setting up his iPad.
For him to be able to use the same apps that you have paid for, and to -mostly- avoid buying things twice, you can set his Apple ID as part of your family on Family Sharing.
The progress of each game will be more difficult or impossible to transfer, depending on how and where it is saved.
The information on the feasibility of that transfer it's probably on each developer support site. You can also try your luck asking for each separately here, but for some reason most games questions are shunned.