After any game closes Ccleaner fully launches and I can't find anything listed to help and I have smart cleaning off
Smart monitoring settings
You have it set to open when acbrowser closes, most games are run in a dumbed down browser page
And where is that setting in the free version? unless it doesn't matter which one it is and I just can't find it atm
The Free version Smart Cleaning is limited in what it can do.
However if it is enabled in Free then it can do as you say if the game creates a lot of temporary files.
Options>Smart Cleaning
Tick everything that Free will let you, then untick them all again (make sure there are none left, not even greyed out ones) and close CCleaner. That should stop Smart Cleaner running in Free.