Can different credit cards for different games. All under the same Apple ID

You cannot delegate what credit card each app should use, but you can change your payment method at any time. For example, if you want to make an in-app purchase on an app, you can change the payment method, then change it back after the purchase.

If you need to change or update your Apple ID payment method - Apple Support

No Problem. The card on top of your payments methods is the one used by default. Not sure if the Support Article made that clear, but it does show the 3 lines to the right of the card that you can use to drag to the top. Once you drag it to the top, then the next purchase will use that card.