Board Game Arena

I’ve noticed recently several games without Complexity listed. Is this just temporary and something that all games will have eventually? I hope so, I like being able to filter for complexity.

It's up to the game developer (or someone in development anyway) to do so. Some developers just don't.

An update on the framework make this value disappear for lot of games without notice to the developers.
It would come back in the future while the Devs take awareness of it