However some games are missing their IGDB ID’s
There is not simple way to achieve this.
All games should have a igdb_id but in many cases won’t.
Either from the game being manually created, or it’s a tool that was added to the categories list and not present on IGDB, or it’s one of the non game categories such as Just Chatting.
So why do you need/what is your use case for the non game categories, this will help us point you in the right direction.